# Old school co2 method.



## Marc Davis

Saw a youtube vid from aquarium coop. Cory visits a shop/gallery that never does water changes (very thick substrate/sand). Also, the shop used upside down water bottles and injected co2 into them and just let it dissolve very slower into the water over the course of the day. Surely this is the most efficient way of saturating the water with co2??

I've been doing this on my tank as well and in 1 week, my plants have gone truly amazing from where they were. I have 2x 2litre diy yeast co2 bottles. I squeeze the bottles in the morning and it fills up the in tank bottle/reservoir for the whole day. 

Am I missing something? Why are more people not doing this. The co2 bubble diffusers make the water look a mess and lots is lost at the water surface. Is it purely an aesthetic thing that people are not wanting the reservoir in the tank?

Here is what I'm talking about.


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## doylecolmdoyle

very cool, guess its a good method if you have that many tanks!


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## zozo

Marc Davis said:


> Am I missing something? Why are more people not doing this. The co2 bubble diffusers make the water look a mess and lots is lost at the water surface. Is it purely an aesthetic thing that people are not wanting the reservoir in the tank?



I guess next to the easthetic part it's about optimalization.. In case working with an in tank diffuser to get optimal co2 conditions you need to spoil a part degassing via the surface again. Provided that you aim for the optimal 30ppm you waste more, but this number is not what you absolutely need its the optimal theoretical average we aim for.. Depending on what you grow and how you like it to grow you could suffice with 15ppm as well for equal results and have less waste. Using a good inline diffuser where the co2 bubbles have much longer water contact in the hose before they reach the tank will desolve beter and also produce less waste than in tank diffusers.

Whit the upside down bottle in the tank as stated in de video is maybe less than 1 litre co2 and it takes several weeks to diffuse by natural means over a rather small water surface contact. Doing some math without going nuts on my pocket calculator this will be adding very little co2.. Every tiny bit helps and can't be wrong the plants definitively will use it. The idea is absolutely ok, but with taking aesthetics into account i'm not so sure if it is that much more benefitial for your plant growth than without it.

It's something worth a try, would be an ideal experiment for in a sump hidden away from view.


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## Edvet

I remember having  DIY yeast CO2 bubbling into a upside down container. It's a way of adding CO2 in low doses which will absolultely work in low light.


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## zozo

Doing a quicky and not going completely to the bottom of it all neglecting temperature and stuff.. Having 1 litre of co2 in gasform hanging in a 50 liitre tank and if it takes 3 weeks to dissolve it should be adding less than 1ppm of co2 per hour. If this has obvious beneficial effects on plant growth only proofs we are overdoing it a bit with the generaly the more the beter adviced constant of 30ppm we all blindly follow..  Than it is in relation to the plant spp. we want to grow for the majority of us a complete waste..

Already thinking of a sump design with a seperate co2 compartment in it.  Encreasing performance by encreasing surface area contact. It's peanuts to build in and nothing realy lost if it doesn't perform enough to write home about..  

Oops i miscalculated it should 0.1 ppm per hour..


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## Zeus.

Marc Davis said:


> Why are more people not doing this. The co2 bubble diffusers make the water look a mess and lots is lost at the water surface



Well in way we are when we have CO2 reactors as his are basically a CO2 reactor with with no flow, plus limited change in [CO2]. Efficient use isnt always to way to go as it takes so long.


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## zozo

At least CO² = 44.1 g/mol 
1 mol gas is 22.4 litre volume neglecting temp for now.

44.1 / 22.4 = 1.96875 g/l = 1968.19 mg co2 in 1 litre gasform.

This all added over a periode of 3 weeks or 504 hours  is 1968/504= 3,9 mg/h  in a 50 liitre tank. 3,9/50=  0,078mg/l per hour.

Isn't it?


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## tam

The owner corrected Cory to say it was lasting a few days, not weeks - about the 1:30 mark - might need to turn the volume up a bit.


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## Marc Davis

tam said:


> The owner corrected Cory to say it was lasting a few days, not weeks - about the 1:30 mark - might need to turn the volume up a bit.


I have to to fill my 500ml bottle once a day.


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## keano

Maybe because it is an eye sore? Why spend money on a gorgeous tank, more money on hardscape and plants. Spend time making a gorgeous aquascape that looks natural, then putting a cock bottle cut in half in it..

I think it uses a lot more CO2 in your method, using half a litre per day as stated in one post is crazy, Ive 1 5kg extinguisher supplying 2 tanks for 3 months so far and its still got a lot of pressure in it.

Whilst for me I use both reactors and diffusers i find the reactor does a better job i like the look of a diffuser and enjoy the bubbles! Same as the twinstar I find it asthetically pleasing and relaxing.

Each to their own..


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## zozo

tam said:


> might need to turn the volume up a bit.


Darn and i thought it stoped with needing reading glasses..  Now i'm on my way for a hearing aid as well.. .. Thanks Tam.. 



Marc Davis said:


> I have to to fill my 500ml bottle once a day.



That woul be a 1000 mg co2 per 24 hours to go easy on it. 41.5 mg/h on a 50 litre = 0.83 ppm/h  Lets rock and roll..

I rather question the 30ppm rule than the .8ppm alternative. In for a try..


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## Edvet

Well low dose CO2 works, it will improve growth. I used a spiral diffusor and about 2 bps on my 400 gallon for a long time. Quite sure it improved growth:


38068787_00005295 by Ed Prust, on Flickr


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## keano

keano said:


> Maybe because it is an eye sore? Why spend money on a gorgeous tank, more money on hardscape and plants. Spend time making a gorgeous aquascape that looks natural, then putting a cock bottle cut in half in it..
> 
> I think it uses a lot more CO2 in your method, using half a litre per day as stated in one post is crazy, Ive 1 5kg extinguisher supplying 2 tanks for 3 months so far and its still got a lot of pressure in it.
> 
> Whilst for me I use both reactors and diffusers i find the reactor does a better job i like the look of a diffuser and enjoy the bubbles! Same as the twinstar I find it asthetically pleasing and relaxing.
> 
> Each to their own..



COKE BOTTLE!


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## zozo

keano said:


> using half a litre per day



Thats half a litre gas.. It doesn't compare to half a litre presurized fluid co2 in the bottle. As said above 44 grams of co2 in gas form takes in 22 litre volume.
Than you need about 1000 litre volume to empty a 2000 gram (2kg) presurized co2 bottle. That would be 2000 half a litre bottles.. 1 a day is 2000 days or appr 3 years with 2kg co2.


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## kadoxu

This 'old school' method is used by a Tropica & also by a TMC CO2 kit.


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## tiger15

keano said:


> Maybe because it is an eye sore? Why spend money on a gorgeous tank, more money on hardscape and plants. Spend time making a gorgeous aquascape that looks natural, then putting a cock bottle cut in half in it..
> 
> I think it uses a lot more CO2 in your method, using half a litre per day as stated in one post is crazy, Ive 1 5kg extinguisher supplying 2 tanks for 3 months so far and its still got a lot of pressure in it.
> 
> Whilst for me I use both reactors and diffusers i find the reactor does a better job i like the look of a diffuser and enjoy the bubbles! Same as the twinstar I find it asthetically pleasing and relaxing.
> 
> Each to their own..


It’s not for show tank.  But if you run multiple planted tanks in a fish room or own a shop, it’s the only practical solution without running the nightmare of multiple hoses, regulators and cylinders. 

Reactor and diffuser may provide efficient high co2 injection, but for low co2 injection, the old fashion is just as efficient. Plant growth is enhanced greatly with slight elevation of co2, so you get more bang for the buck by injecting low rather than high co2 and from that perspective, old fashion is relatively more efficient.


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## zozo

Maybe a completely crazy idea.. But seeing it function submersed, the co2 chamber full with co2 slowly fills from the open bottom up with water again while the co2 slowly dissolves. Than the floater in the bottle is your visual marker. 

Now just thinking of vacuum? Placing that co2 chamber only an inch bellow the water line, suck it vacuum and it fills with water. Attach the co2 bottle and fill it with co2 from the top.. So the vacuum will be replaced with co2.

Will it vacuum up again and fill with water with the co2 dissolving?

If so there is no need to submerse the complete botlle in the tank..


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## Edvet

Didn't the video show a bottle with a stone above the waterline?


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## zozo

Edvet said:


> Didn't the video show a bottle with a stone above the waterline?


Duno there was so much to see in the video.. Have t watch again..

Anyway now i want to know.. I'm off to the lfs for a small can of co2..


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## tam

Brilliant, I love experiments. I'm predicting that yes, it would fill with water, can't fill with air so it has to (I think). It's like the upside down dome/tank koi viewers - they use a dome on a floating raft.


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## Marc Davis

tam said:


> Brilliant, I love experiments. I'm predicting that yes, it would fill with water, can't fill with air so it has to (I think). It's like the upside down dome/tank koi viewers - they use a dome on a floating raft.


I think this is correct. If it can't fill with air, it has to either fill with water....or more co2


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## Marc Davis

tiger15 said:


> It’s not for show tank.  But if you run multiple planted tanks in a fish room or own a shop, it’s the only practical solution without running the nightmare of multiple hoses, regulators and cylinders.
> 
> Reactor and diffuser may provide efficient high co2 injection, but for low co2 injection, the old fashion is just as efficient. Plant growth is enhanced greatly with slight elevation of co2, so you get more bang for the buck by injecting low rather than high co2 and from that perspective, old fashion is relatively more efficient.


I'm using in my show tank. Ok, my tank isn't up there with some of the tanks on here but I've only been fish keeping a year and the tank is only 3 weeks old.

Here it is. I've tried to hide it behind the swords on the left. Don't think it's too much of an eye sore.


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## zozo

tam said:


> Brilliant, I love experiments. I'm predicting that yes, it would fill with water, can't fill with air so it has to (I think). It's like the upside down dome/tank koi viewers - they use a dome on a floating raft.


Did it one time with a 25 litre tank standing opside down on a frame.. Fun for a day or 2 maybe 3 or 4 than water starts to degass in the tank making it a mess with brown foamy slime gas bubbles accumulating at the top. I guessed it was oxygen etc. gasses plants etc. release into the water column. Even tried a pump bellow it so it would have circulation. But it encreased that degassing process actualy. SInce it was such a mess in short time i dropped the Gold fish skybox. But it was funny to see them swinning above the actual surface..

Repalcing the vacuum with co2 i guess the same, if it desolves it must replace with water and fill up again. I can't think of a valid reason why it shouldn't, but it's a part of physics i'm not sure of these logics apply..

But we shortly will know.. Can't take long with a small amount of co2..


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## tiger15

zozo said:


> Maybe a completely crazy idea.. But seeing it function submersed, the co2 chamber full with co2 slowly fills from the open bottom up with water again while the co2 slowly dissolves. Than the floater in the bottle is your visual marker.
> 
> Now just thinking of vacuum? Placing that co2 chamber only an inch bellow the water line, suck it vacuum and it fills with water. Attach the co2 bottle and fill it with co2 from the top.. So the vacuum will be replaced with co2.
> 
> Will it vacuum up again and fill with water with the co2 dissolving?
> 
> If so there is no need to submerse the complete botlle in the tank..


CO2 dissolves better under pressure than tension. I used to run siphon tubes in my old fashion filter, air pocket tends to form on the top of the siphon tubes due to tension, so I can predict that emerged bottle under vacuum will dissolve CO2 very slowly, and not completely.

The best way to secure a submerged bottle is not to use suction cups but to drill tiny holes on the tank rim and tie with a fish line. You can let it slide up and down with changing buoyancy or put a stopper to prevent movement.


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## sparkyweasel

If the bottle was above the water level, yes it would suck up water as the CO2 gets dissolved, but gravity pulling that water down will reduce the pressure of the CO2, and I think that will slow the rate at which it dissolves. With the bottle submerged water is pressing up against the CO2, slightly increasing the pressure. I wonder how much difference it would make? Probably not much I guess.


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## Marc Davis

sparkyweasel said:


> If the bottle was above the water level, yes it would suck up water as the CO2 gets dissolved, but gravity pulling that water down will reduce the pressure of the CO2, and I think that will slow the rate at which it dissolves. With the bottle submerged water is pressing up against the CO2, slightly increasing the pressure. I wonder how much difference it would make? Probably not much I guess.


For that matter then, you could argue that the lower you have bottle in your tank, the more pressure/dissolved co2 you get??


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## tiger15

Marc Davis said:


> For that matter then, you could argue that the lower you have bottle in your tank, the more pressure/dissolved co2 you get??


You are absolutely right.  Place your bottle, diffuser, reactor or whichever to inject co2 at the lowest point to effect the highest solubilty of co2.  Tension, or negative pressure, has the opposite effect of pulling gases out of water.

Solubilty of co2 is sensitive to temp and pressure and you can find many charts in the web to depict the relationship.


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## zozo

I was thinking the same thing, that a vacuum refilled with co2 that gravity and pressure how tiny it is would have some effect.. But why not put to the test and see how far it goess..



 
Was vacuum and now filled with co2.. 


 
But for € 4.75 for a can with 5 gram of co2 this is not going to be my hobby. The can is more expensive than its contents.. 

And indeed weight it down and let gravity play probably would help the co2 dissolve beter by the pressure.


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## ian_m

I think the CO2 concentration may be a tad more than the quoted 0.8ppm roughly calculated above, possibly.

You can calculate how much CO2 dissolves in water at 1 atmosphere by Conc = Pressure / solubility. For CO2 solubility is 29.41 atmospheres / mole.

Thus conc = 1 atmosphere / 29.41 -> 0.034 M

Multiplying by atomic mass of 44 gives 1.5ppm.

However it will be less (0.8ppm ) as gas will be continuously lost from surface and also some CO2 will dissociate/combine in the water to carbonic acid. Someone want to help me out how to calculate the carbonic acid contribution ?

In the end is likely to be significantly less than the 30ppm we high tech tank owners inject.


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## zozo

0 atmosphere is 1 absolute, in both cases water and co2 are under the same atmosphere, doesn't that equal 0?

I'm realy not that of a physic and math wizard, tho these kind of calculation were part of my education it all is much to long ago. I've forgotten what i've all have forgotten, that long.  Just gave it a go with what i could find on how much volume a mol is.. To show approximately it aint realy adding that much. As you say there is much more to it having influence but it wont make that of a huge difference..

Same as land above see level has less atmospheric pressure has effect on disolved oxygen in water. But for us neglectable tiny amounts at inhabitable areas on the planet it equals by few Mg almost total saturation. You must be awfully high up in the mountains for any significant difference.


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## Zeus.

tam said:


> I'm predicting that yes, it would fill with water, can't fill with air so it has to (I think)



My CO2 reactors must get 1/4 full of CO2 by end of CO2 period all gone by next day, cant see it being any different with these jars

Diffusion from high [CO2] to low [CO2] with the limiting factor being how fast it takes to diffuse into water OFC, Boyles Law in there somwhere


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## zozo

Well what do you say..
3.50PM




3 hours later at 7.05pm




Not that i yet see any plants grow..  but definitively something going from the bottle into the tank and visa versa.

I wonder where we are tomorow morning..  Might do a pH profile next.. The darn thing hangs next to it anyway..


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## sparkyweasel

Measuring the water level in the bottle gives you an easy way to calculate how much CO2 has dissolved into the water.


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## zozo

Got 3 low techs, averagely i measure pH 8.5 - pH 8.3 during day times in all of them.. I didn't measure the start value of this one because actualy didn't expect much. I assume it started around the pH 8.3 as showen in above pics... But now i measure pH 7.8... Half a unit in 3 hours time.. 





Didn't expect that at all.. It's a 25 litre tank.. Temp is 26°C in this heatwave lately..

Remarkable result, especialy with the vacuum idea.. prediction were it should work lesser.. I'll put it to the test and see..


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## zozo

Ph still dropping at 7.7 currently..


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## Zeus.

Marc Davis said:


> For that matter then, you could argue that the lower you have bottle in your tank, the more pressure/dissolved co2 you get??



Yep that's Bolyes law kicking in.

Zozo
Impressive pH drop wasn't expecting that much. Does the tank with the CO2 bottle in feed other tanks? Looks like it might. If it does a pH profile of that tank would be insightfull 

A small concern I have is the fluctuating [CO2] of the tank dependant on the actual [CO2] getting to the plants


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## zozo

Zeus. said:


> Zozo
> Impressive pH drop wasn't expecting that much. Does the tank with the CO2 bottle in feed other tanks? Looks like it might. If it does a pH profile of that tank would be insightfull
> 
> A small concern I have is the fluctuating [CO2] of the tank dependant on the actual [CO2] getting to the plants



It's a stand alone 25 litre tank on day light next to an east fased window with a small hob. Still dropping at pH 7.5 now..


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## zozo

starting at 3 pm day before and this is 8 am next day

pH 7.7 and a nearly co2 empty bottle in 17 hours.




Seems a rather effective method, is it because of the vacuum? I expected it to last several days as stated in the video.Completely underestimated it..
Lets fill it up again..


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## ian_m

Interesting.

What colour is your drop checker ?

You could use multiple drop checkers with indicator/solution diluted 50:50 with distilled water to read colour change at 30ppm, 15ppm and 7.5ppm ?


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## Marc Davis

zozo said:


> starting at 3 pm day before and this is 8 am next day
> 
> pH 7.7 and a nearly co2 empty bottle in 17 hours.
> View attachment 116640
> 
> Seems a rather effective method, is it because of the vacuum? I expected it to last several days as stated in the video.Completely underestimated it..
> Lets fill it up again..



Same rate of disolvation as mine. I refill my in tank bottle from the yeast/sugar mix that has been pressurising from the previous day. Quick squeeze in the morning and I'm set for the day  (check valve stopping back syphon )


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## zozo

ian_m said:


> Interesting.
> 
> What colour is your drop checker ?
> 
> You could use multiple drop checkers with indicator/solution diluted 50:50 with distilled water to read colour change at 30ppm, 15ppm and 7.5ppm ?



Haven't yet installed one.. And i have to search for it, i have only one left somewhere. Not have used any co2 for over 2 years.. Than i have to make me some fluid too.
Seeing the ph profile from previous experience it think it should be on the tipping point of green.  I'll cook me up some dkh4 and see what it tells us.


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## zozo

Marc Davis said:


> Same rate of disolvation as mine. I refill my in tank bottle from the yeast/sugar mix that has been pressurising from the previous day. Quick squeeze in the morning and I'm set for the day  (check valve stopping back syphon )



Well so far the easthetic problem looks partialy solved.. Having the bottle above the surface works as good.. 

The results so far makes me want to experiment with a vacuum co2 chamber in the sump.. Seeing the rate it dissolves this could easily be automated to refill at the same rate it dissolves.. In the sump invironment parameters at least can be kept relative stable regarding temp swings.


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## Zeus.

Impressive result, if the tank had plants in the CO2 would be used faster during photoperiod! or I would  expect to be


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## zozo

Zeus. said:


> Impressive result, if the tank had plants in the CO2 would be used faster during photoperiod! or I would  expect to be



Yes it obviously would, i stripped this little tank down from a lot of plants lately and gave them away. It indeed is very sparsly planted.. Now it only contains a few plants dwarf sage, crypts and some mosses. It's my plant bin for things i don't like to dispose off... I'll drop in an extra bunch of potamogeton gayi from the garden and some bacopa. Got to much of it anyway.. 

But as stated in the video, it seems to dissolve quicker with more demanding plants in the tank.. In how far it equals out the numbers i have no idea..


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## zozo

did put some more consumers in it.. Later on i will put in the drop checker.. For now it stabelized steadily at pH 7.7 in this natural rather low light cycle.


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## zozo

Another point of concern, the bottle doesn't only releas its co2 contents to the water, the water also degasses back into the bottle. As shown in the pictures above it doesn't empty completely after 24 hours about 1/4 of the bottle is still filled with gas. Than you if refill it from bellow, but it aint only co2 what's left in there. It possibly is part co2 and part oxygen etc. the water degasses back into the bottle. Thus refilling it with this so called poluted co2 bubble left in the bottle you put less co2 back.

I noticed a signicficant 0.4 less pH drop after the 3th refill.. This can only proof the above. Took the bottle out and started with a full fresh co2 refill again the pH drop was again as before.

So for optimal result you should empty old gas left in te bottle before you refill..

Best practice for this method would be installing a hose connetor to the bottles top side with a small valve. Degass it and refill it from above and not from bellow with the a bubble left in there..


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## ian_m

zozo said:


> Another point of concern, the bottle doesn't only releas its co2 contents to the water, the water also degasses back into the bottle. As shown in the pictures above it doesn't empty completely after 24 hours about 1/4 of the bottle is still filled with gas.


Well spotted & deduced batman, as they say !!!.

I suspect you will find it will be both nitrogen and oxygen being released from the water as these are about 100 times less soluble than CO2. Next time you end up with this left over "gas"  stick a burning match in it and see if it extinguishes the match, I suspect it will be nitrogen whose solubility is less than oxygen, (0.02ppm as opposed to oxygen 0.04ppm), thus will not so easily re-dissolve back in the water.


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## zozo

Thank you ian_m.. 



ian_m said:


> stick a burning match in it and see if it extinguishes the match,


But if you manage to get a burning match in there like this



You're probably going to make David Coperfield feel very invious..

btw this pic was after the first night over.. Noticed the left over bubble getting bigger the 2nd night over after that..


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## tam

The Tropica version of this says it needs to be vented once a week, which I guess is to resolve that issue: https://tropica.com/en/plant-care/co2/system-60/


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## zozo

tam said:


> The Tropica version of this says it needs to be vented once a week, which I guess is to resolve that issue: https://tropica.com/en/plant-care/co2/system-60/



Once a week? seems a bit long to what i experienced. Seen the pH drop from 8.3 to 7.6 and after the 3th refill it stopped dropping at 8.0. Relatively a drastic reduction quite soon. I would rather say vent it daily or at least once every 2 days.

Or monitor it and decide from there when it's necessary..


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## Zeus.

Trouble with having the bottle above the water is there will be a negative pressure once the water rises above the level of the water in the tank so it may be hard to get all the CO2 to dissolve. If/when the bottle is emersed in water completely the pressure of the CO2 in the bottle will be higher so it should dissolve better - well thats my thoughts on it


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## Marc Davis

Zeus. said:


> Trouble with having the bottle above the water is there will be a negative pressure once the water rises above the level of the water in the tank so it may be hard to get all the CO2 to dissolve. If/when the bottle is emersed in water completely the pressure of the CO2 in the bottle will be higher so it should dissolve better - well thats my thoughts on it



your typical drinking bottle is going to stand out in the water, yes. But the tropica "box" is really quite discreet. Especially if the tank is heavily planted. Im going to buy the system later i think just for the box. Once the co2 spray can has run out, ill just attach my yeast/sugar bottles to it.


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## zozo

I saw the colombo version in the LFS also very discrete little container. Smaller then 500cc it looks like a 250cc to me, but didn't check . Tho i might also effectively only fill 400cc in a cut pet bottle.. I bought the colombo refill can..

But seeing the pH profile, it is remarkably stable during the intire light cycle.. If refilled every morning and the bottle slowly empties the co2 and refills with water. By the time it reaches the point it reduces the pH the light cycle is over. Next morning when it needs a refill pH is back at 8. From that perspective it kinda works a charme, having an almost 1 unit drop.. Since it is in my case from a rather high over pH8 starting point it aint enough to make the dropchecker react very much it stays in the blue range. But for a small low energy tank i guess it's a decent helping hand.

I'll give it a try with the bottle submersed and see if the water gasses out less into the bottle. Not going to make predictions, was far off with the first one too, this time i look before i leap.. 

But a vent is necessary anyway.. I don't see much waste venting it every 2 days to have the optimum out of it. It is a darn waste with using the spray cans, that's a complete rip off, no fun with almost € 1 for 1 gram of Co2.


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## techfool

I've used the tropica thing and it is quite discreet. Plus the shrimp liked to sit in it.


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## zozo

Zeus. said:


> Trouble with having the bottle above the water is there will be a negative pressure once the water rises above the level of the water in the tank so it may be hard to get all the CO2 to dissolve. If/when the bottle is emersed in water completely the pressure of the CO2 in the bottle will be higher so it should dissolve better - well thats my thoughts on it



Reading back on @Marc Davis reply and his 500cc submersed coke bottle empties in about the same time span.. Than i doubt there will be a huge difference.. Anyway the pressure on the surface is 1 atmosphere, so the updraft pressure in the vacuum bottle on the co2 is the same. Since 1 atmosphere is 10 metre water column, it is easy to calculate the extra pressure if 12 cm submersed.. So each cm depth is 1/10000 bar extra..


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## Zeus.

zozo said:


> So each cm depth is 1/10000 bar extra.



which is what I would of thought, not much  but how much does the pressure difference effect Bolyes law, again probaly 'not much' but we are not talking about a fast experiment uptake rate anyway.


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## Edvet

zozo said:


> Anyway the pressure on the surface is 1 atmosphere


So submerging the bottle will increase pressure , not as much as a diver going to the Mariana trench, bit there will be an increase


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## Edvet

https://www.shogun.nl/luchtbuksen/benodigdheden/co2-patronen.html?limit=all
this should be cheaper than the Dennerle can.
Or this:
https://www.blokker.nl/p/patronen-v...K76sKHgJwvx5fRlF27LeYLRVXD3B7t6BoCFbQQAvD_BwE


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## zozo

I was more aiming my arrows on this, since i live close to the border i have a German delivery address, no international shipping cost as local a pic up. 
https://www.ebay.de/itm/Kohlensaure...910803?hash=item56b2338ed3:g:468AAOSwX0xbPEIq



Edvet said:


> So submerging the bottle will increase pressure , not as much as a diver going to the Mariana trench, bit there will be an increase



Probably, i'm not into the mater enough to say something conclusive about it.. As said each 10mm down is a 0.0001 bar pressure buld up. If you can speak of a pressure increas, relatively.. I have no idea on the numbers of the force needed for co2 compresion as in boyls law. There obviously will be a form of counter pressure by the gas. I would need to dig realy hard for numbers and formulas. To calculate which force is the greatest.

For now obviously the upwards pressure on the co2 in the vacum is 1 atmosphere. If the level of co2 is 15cm bellow the surface it will be 1.0015 atmosphere.. I guess the whole only can be theoreticaly calculated without an accurate barometer measuring the invironmental air pressure which next to that never is constant. Without it we assume it is 1.. If it isn't you always will be a few 1/10000 units off.

Neglecable if you ask me.. If it wasn't we didn't use 1 as a starting point for calculation.  And an atmosphere pressure sensor would be common tool  as must have.


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## Marc Davis

I brought the tropica system guys. Really nicely built and I don't think it stands out much at all.


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## tiger15

zozo said:


> I was more aiming my arrows on this, since i live close to the border i have a German delivery address, no international shipping cost as local a pic up.
> https://www.ebay.de/itm/Kohlensaure...910803?hash=item56b2338ed3:g:468AAOSwX0xbPEIq
> 
> 
> 
> Probably, i'm not into the mater enough to say something conclusive about it.. As said each 10mm down is a 0.0001 bar pressure buld up. If you can speak of a pressure increas, relatively.. I have no idea on the numbers of the force needed for co2 compresion as in boyls law. There obviously will be a form of counter pressure by the gas. I would need to dig realy hard for numbers and formulas. To calculate which force is the greatest.
> 
> For now obviously the upwards pressure on the co2 in the vacum is 1 atmosphere. If the level of co2 is 15cm bellow the surface it will be 1.0015 atmosphere.. I guess the whole only can be theoreticaly calculated without an accurate barometer measuring the invironmental air pressure which next to that never is constant. Without it we assume it is 1.. If it isn't you always will be a few 1/10000 units off.
> 
> Neglecable if you ask me.. If it wasn't we didn't use 1 as a starting point for calculation.  And an atmosphere pressure sensor would be common tool  as must have.



Your estimate is too simplistic and can't be correct.  When you open a can of soda, CO2 bubbles are released due to reduced pressure.  CO2 is under slight pressure in the can, probably no more than at the bottom of a fish tank for safety concern. 

Boyls law defines the relationship of gas pressure and volume. It's a universal law applicable to all gasses.  The relationship of CO2 solubility and pressure is governed by the properties of specific gas (CO2 in this case) that vary from gas to gas.  There are also other influencing factors such as temperature, partial pressure of CO2, and concentration gradient at the air water interface.  It's complicated and the only sure way is to figure out is to conduct experiments to compare CO2 concentrations under different depths.


----------



## zozo

tiger15 said:


> Your estimate is too simplistic and can't be correct.



I actualy have no clue which estimate i made you are refering to.. The estimate that water presure in an aqaurium is neglectable because it is so little to make a fuss about it? I guess it must be that one i didn't made another estimate in that comment.  And concerning this i hold my ground that it is in relation to the whole Co2 concept as we practice it in the hobby.. It is overall based upon estimates, as for example the dropcheckers color or the use of the Ph/kH profile chart.


----------



## Edvet

The proof is in the pH profile as far as i am concerned.


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## tiger15

zozo said:


> . The estimate that water presure in an aqaurium is neglectable because it is so little to make a fuss about it?


When you say there is negligible pressure difference in a fish tank, it implies there is negligible impact on CO2 solubility so why make a fuss about it.  You don’t know until you do a pH profile check on the impact.


----------



## zozo

tiger15 said:


> When you say there is negligible pressure difference in a fish tank, it implies there is negligible impact on CO2 solubility so why make a fuss about it.  You don’t know until you do a pH profile check on the impact.



It probably has an minor impact on co2 solubilty, but it will be very minimal in an aquarium.. And since we are talking fractions of 1/10000, it is percentages of milibars and is indeed is nitpicking. Then suppose i submerse a bottle in my test object which is barely larger than the bottle height i can't submerse it completely without the open side of the bottle toughing the substrate.

Anyway since the atmospheric pressure on the tanks surface water has influence on the natural watercolumn pressure i have no way to tell what i'm looking at without a very accurate barometer. Since depending on this condition in between weather fronts can have a differnce of 100mm/millibar pressure difference i also have this pressure differnce bellow the water surface a few cm bellow it. Than the pH profile doesn't tell me much, becuase the pressure doesn't have a constant. The fluctuating atmospheric pressure on he water surface can be greater than the static very tiny watercolumn pressure in the tank. Thus it fluctuates.. Than it would be needed to monitor both and track it a rather long periode and make an average to be conclusive. Be my geust and put it to the test, you might find out that in cold days the co2 solubility is greater than in warm days. It probably is in average always with a few ppm, also when we use other means than this old school co² method.

That is not an estimate but i physical fact we can not get around and i don't like to dispute about because it is to far out off the workings of my brain..

And since we have no hobby means to determine this with very concusive numbers we all just stop at looking at a drop checkers color or at a pH profile. If it's green it's good enough for <Henderson–Hasselbalch>  than it must be good enough for me.. And it is.


----------



## zozo

And read back @Marc Davis comment, he has a bottle submersed with the same amount of co2 in it and he has to refill it in the same rate as a bottle Emersed with a vacuum.. Why should i test that agian.. He answered the qeustion that is fairly the same in both way the bottles are equaly empty in the same time.. If it was so much beter he would need to refill iit more often, since he doesn't.. Why should i try again what he is doing and say "Yes you are correct".. That's what's called trying to reinvent the wheel..


----------



## tiger15

zozo said:


> And read back @Marc Davis comment, he has a bottle submersed with the same amount of co2 in it and he has to refill it in the same rate as a bottle Emersed with a vacuum.. Why should i test that agian.. He answered the qeustion that is fairly the same in both way the bottles are equaly empty in the same time.. If it was so much beter he would need to refill iit more often, since he doesn't.. Why should i try again what he is doing and say "Yes you are correct".. That's what's called trying to reinvent the wheel..


You can’t go by frequency of refilling, as the density of co2  submerged is higher than emerged. So more co2 mass is filled submerged than emerged.  Onlly pH comparison can tell the difference assuming you have a high resolution pH meter, and that you submerge all the way to the bottom of a deep tank.  Submerging just beneath the surface or to the bottom of a shallow tank will not likely show any measurable difference. This is evident when you use an air stone, as the bubbles expand as they rise due to reducing pressure following Boyd’s law.


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## Edvet

Got the cheap Colombo set. Starting pH is 7.5.


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## zozo

tiger15 said:


> You can’t go by frequency of refilling, as the density of co2  submerged is higher than emerged. So more co2 mass is filled submerged than emerged.  Onlly pH comparison can tell the difference assuming you have a high resolution pH meter, and that you submerge all the way to the bottom of a deep tank.  Submerging just beneath the surface or to the bottom of a shallow tank will not likely show any measurable difference. This is evident when you use an air stone, as the bubbles expand as they rise due to reducing pressure following Boyd’s law.


Finaly you got me there!!!....  I admit you are absolutely right.. 0.0015 extra atmosphere compresses the co² so you get more of it in the same volume... You are correct.. And i don't know how and also don't want to put the energy in it to calculate how much..
You may do that for us.. Or maybe you know already, but are not telling just to keep the exitement up..


----------



## ian_m

tiger15 said:


> This is evident when you use an air stone, as the bubbles expand as they rise due to reducing pressure following Boyd’s law.


This got me pondering, there is now way this can be true. Bubbles do not change volume due to Boyles law in rising up a fish tank, it is way way not deep enough to have any visible effect.

Boyles law states Pressure times volume (PV = k) is a constant for a gas at fixed temperature.

Thus at top of tank for a bubble of volume V(top) -> P(top) x V(top) = k.
Similarly at bottom P(bot) x V(bot) = k.

Thus P(top) x V(top) = P(bot) x V(bot)

If pressure at top of tank is 1 atmosphere, pressure at bottom for 50cm (0.5m) tank will be 1 atmosphere + (0.5 m / 10m) -> 1.05 atmospheres. (10m of water adds 1 atmosphere).

Volume of spherical bubble is 3/4 π R^3. (R = radius).

If we assume a bottom bubble radius of 1mm and ignoring the 3/4 π bit (as both sides of the equation) you get

R(top)^3 = R(bot)^3 x 1.05.

Take cube root.

R(top) = 1.016mm.

Hardly a big increase in radius !!! A 5% increase in volume.

However, you will perceive an increase in size as often the bubbles do not stay spherical but flatten out into saucer shapes.

Slightly different with a fizzy drink as the rising CO2 bubbles pick up more gas as they rise.


----------



## zozo

ian_m said:


> If pressure at top of tank is 1 atmosphere, pressure at bottom for 50cm (0.5m) tank will be 1 atmosphere + (0.5 m / 10m) -> 1.05 atmospheres. (10m of water adds 1 atmosphere).



In all excitment i added a 0 to much. Since 1 cm water column is 1/1000 bar.. Proofs i'm getting to old for this cr*p?  Only tried to explain that as long as we keep 1 atmosphere as average starting point and don't measure the true present atmospheric pressure than the aqaurium depth or its water culomn pressure is neglectable. Because you might have 1050 millibar at this location and  970 millibar atmospheric presure at a different location at the same time.

That difference in atmospheric pressure covers about every normal household aquarium size. So 99% you might just always be slightly incorrect in such a nitpick calculation. But it doesn't seem to sink in. Mean while i'm wondering myself why the hell am i trying to explain this after all..  I give up..


----------



## Edvet

pH 6.8 this morning
It's a 50 lit tank and the small holding canister sits in the flow. The canister was empty this morning ( filled it 15.00 hours yesterday).


----------



## cheekycharly

Got to this post after being amazed at the same video from aquarium co op. Has anyone found a well presented co2 chamber like the tropica one but a bit larger as I was going to try this on my 180L Rio that has no Co2 currently and do before and after.


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## Zedan

Marc Davis said:


> I brought the tropica system guys. Really nicely built and I don't think it stands out much at all.
> View attachment 116714



How are your plants looking 6 months on? I'm curious about using this system to ease my plants into submersed life when I flood my dry start tank.


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## Marc Davis

Zedan said:


> How are your plants looking 6 months on? I'm curious about using this system to ease my plants into submersed life when I flood my dry start tank.


They went from this:


 

To this in about 2 months:


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## Cheltster

. Marc was that just with the Tropica Co2 diffuser in the corner or did you add liquid carbon or go full FE? 

I have total tank envy BTW.


----------



## Zedan

Marc Davis said:


> They went from this:
> View attachment 121311
> 
> To this in about 2 months:
> View attachment 121312


 
Wow that turned out amazingly! Was this just with the tropica kit? What else are you using?


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## Marc Davis

Zedan said:


> Wow that turned out amazingly! Was this just with the tropica kit? What else are you using?



Just some chelated trace elements (tropica premium). I never use NPK in my tanks. Just causes algae everywhere (i know lots dont agree with this, but ive witnessed it loads of times now)

It also has 2x led 20w floodlight lamps from Homebase. thats it.

After the co2 canister ran out from the tropica kit, i just made my own co2 with sugar and yeast and have been ever since.

Here is the tank now, went for a nature aquarium look rather than dutch:


----------



## Zedan

Marc Davis said:


> Just some chelated trace elements (tropica premium). I never use NPK in my tanks. Just causes algae everywhere (i know lots dont agree with this, but ive witnessed it loads of times now)
> 
> It also has 2x led 20w floodlight lamps from Homebase. thats it.
> 
> After the co2 canister ran out from the tropica kit, i just made my own co2 with sugar and yeast and have been ever since.
> 
> Here is the tank now, went for a nature aquarium look rather than dutch:
> 
> View attachment 121329



Love it! What are your thoughts on the tropica kit, would you recommend it?


----------



## Marc Davis

Zedan said:


> Love it! What are your thoughts on the tropica kit, would you recommend it?


yes def. I still use the co2 bell to collect my diy co2. It is nice and compact with clear suckers that full secure it to the aquarium. i keep it at the back hidden by plants. I dont really understand why anyone would do a planted tank with at least diy co2. The difference between having it and no co2 is night and day.


----------



## zozo

Marc Davis said:


> yes def. I still use the co2 bell to collect my diy co2. It is nice and compact with clear suckers that full secure it to the aquarium. i keep it at the back hidden by plants. I dont really understand why anyone would do a planted tank with at least diy co2. The difference between having it and no co2 is night and day.



The Fox and the Grapes.. 

The ones succesfull advocate it, the ones failing advice against. In most cases people tend to think their personal experiences must be universal.
It's in the same realm as the "What causes alga?" discussion, often with conclusions based upon opinions, again based upon experience. With to many invissible factors cuasing succes or failure.

There is always exeption that proves the rule.

Anyway, good job! Looks realy nice..


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## Daveslaney

Elos do a co2 reactor style that works on a simular principle to the bottle but expensive though.
https://www.elosaquarium.co.uk/CO2-Venturi-Reactor-Large


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## michaelc

I saw the same you tube video made by Cory form Aquarium Co-op. Watching it made me finally make up my mind to go for a Tropica type Aerosol CO2 set up (Those tanks are incredible at Ocean Aquarium). This is the first time I have tried a CO2 set up.

The difference CO2 made to my plants in my Fluval Chi was remarkable. It really is quite something to see, and  the changes are very quick too. Plant growth is much faster, but even more amazing to me was to see how healthy the plants became- They are so green now, and the stems of the plants are so thick, whilst the leaves look really plump and healthy. 

The bottom line here is that this diffuser technique does work. I was a bit sceptical at first, looking at the size of the diffuser and the small area of contact that the water has with the gas. All doubts answered and then some. I'm loving the difference. Brilliant!

If you entertain any doubts about trying the diffuser system, and you don't want to accept my anecdotal evidence (and why should you!) watch the video again - look at all the tanks in the shop. Enjoy! Good luck all.


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## akwarium

in theory the surface area should be around 2% of the total surface area to get a CO2 level of 30 ppm, just theory. In reality it will be lower.


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## Edvet

akwarium said:


> 2% of the total surface area to get a CO2 level of 30 ppm


I don't think this will get you to 30 ppm, it's very hard to actually get to 30 ppm without forcing it. All those "charts" which used color conversion to get to 30 ppm are wrong. On the other hand just getting a small increase is already beneficial.


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## akwarium

Earths atmosphere contains around 0,037 % CO2, at a pressure of 1 atm, and a water temperature of 25 C the equilibrium between the CO2 in the atmosphere and the amount of CO2 dissolved in water is 0,5 ppm. 

If the amount of CO2 in the atmosphere rises the amount of CO2 dissolved in the water will rise to. 

For example: if the air would contain 4% CO2, like the air we breath out,  CO2 levels in the water would be over 60 ppm
and if the atmosphere would be 100% CO2, we would get an equilibrium around 1600 ppm.

To get the desired 30 PPM  2% of CO2 in the atmosphere is needed, it might not be very practical to create CO2 levels of 2% in our living room....
So we cheat, we create a second atmosphere. This is the old school diffuser, a small atmosphere of 100% CO2.

The trick is to create a situation wherein the average CO2 level of the atmosphere in contact with the water in the tank is 2%. With one atmosphere containing around 0.037 % and one atmosphere containing 100% of CO2, the math is fairly simple. The surface area of the diffuser should be (a little under) 2% of the total surface area.

But, this is just theory,  there are some aspect that are not accounted for:

1. the air inside the diffuser won't be 100% CO2 for long, other gasses dissolved  in the water will enter the diffuser.
2. there is a difference in speed between CO2 dissolving from the diffuser into the water, and from the water in to the air at the rest of the surface. this can also be influenced by water movement etc.
3. the water in an aquarium is not 100% pure, it contains small amounts of salts that have a negative effect on the solubility of CO2
4. consumption/production of CO2 by plants, bacteria and fish is not accounted for.

In reality the surface area of the diffuser should be 20% larger (as a rule of thumb)

Old school as it may be, this is still a great way of adding CO2 to small low tech tanks, there is virtually no risk of overdosing, no constant CO2 monitoring is required and it is very compatible with diy CO2 based on yeast and sugar.


----------



## Mark Stoakes

Marc Davis said:


> They went from this:
> View attachment 121311
> 
> To this in about 2 months:
> View attachment 121312


Nice looking with quite a big improvement, how many litres is that tank marc


----------



## dw1305

Hi all, 





akwarium said:


> Earths atmosphere contains around 0,037 % CO2, at a pressure of 1 atm, and a water temperature of 25 C the equilibrium between the CO2 in the atmosphere and the amount of CO2 dissolved in water is 0,5 ppm.
> 
> If the amount of CO2 in the atmosphere rises the amount of CO2 dissolved in the water will rise to.
> 
> For example: if the air would contain 4% CO2, like the air we breath out, CO2 levels in the water would be over 60 ppm and if the atmosphere would be 100% CO2, we would get an equilibrium around 1600 ppm.


That is right, it is <"Henry's law">, the level of CO2 in the atmosphere is over now 0.04% (400ppm) and still rising. You can dissolve a huge amount of CO2 in water, just think of a carbonated drink.






akwarium said:


> The trick is to create a situation wherein the average CO2 level of the atmosphere in contact with the water in the tank is 2%. With one atmosphere containing around 0.037 % and one atmosphere containing 100% of CO2, the math is fairly simple. The surface area of the diffuser should be (a little under) 2% of the total surface area.
> 
> But, this is just theory, there are some aspect that are not accounted for:
> 
> 1. the air inside the diffuser won't be 100% CO2 for long, other gasses dissolved in the water will enter the diffuser.
> 2. there is a difference in speed between CO2 dissolving from the diffuser into the water, and from the water in to the air at the rest of the surface. this can also be influenced by water movement etc.
> 3. the water in an aquarium is not 100% pure, it contains small amounts of salts that have a negative effect on the solubility of CO2
> 4. consumption/production of CO2 by plants, bacteria and fish is not accounted for.


I'm not a CO2 user, but I think that is right. You can largely ignore the effect of atmospheric pressure and TDS, unless you liive in Denver and/or keep Marine aquariums.

cheers Darrel


----------



## Aqua sobriquet

Just thinking out loud here but has anyone checked the amount of CO2 in sparkling water from the supermarket?


----------



## zozo

Aqua sobriquet said:


> Just thinking out loud here but has anyone checked the amount of CO2 in sparkling water from the supermarket?



It depends on the brand and than it depends on the version, same brand can make bubble strong and bubble light water.  Thus than you need to see if the label tells you something about it.. Most likely not so much. But  Take for example Spa reine brand from Belgium.

We once had a journalist investigating pressure in sprankling water bottles, he investigated Spa because this was about the fierced sprankling water out there. Because they hush about it.. Also about the CO² content values, even a phonecall to the service hot line they didn't tell. But they do give the HCO3- content in 18mg/l.

Than if you know the pH of the water the CO² content can be calculated.  It measured pH 4  They calculated it back to 4gr or 4000mg/l CO² giving it an overhead pressure about 2,5 bar.

I do not know the formula..  I guess they need more than pH only. Maybe KH too is enough. The journalist probably brought the story and bottle to a lab and they did the calculation and gave him the results.

Brands as Perrier or Pellegrino have far less in it.


----------



## X3NiTH

Not specifically but I do use carbonated water to help dissolution of Calcium and Magnesium Carbonate for my remineralisation strategy. I use a Sodastream machine (and their plastic bottles) to carbonate 900ml of cold refrigerated water to the maximum pressure the machine can deliver (vents at a set pressure, don't know what the pressure is but it will be to prevent overfilling and rupturing the plastic bottle), I then add the carbonates and some Ascorbic acid and put back in the fridge for a while to give time for some dissolution. Once I have added all that I need to for my remineralisation and the addition of the CO₂ laden carbonate/bicarbonate milk like juice from the fridge to 25L RO/DI to dKH/GH8 then this water contains approximately 30-35 ppm CO₂ (I have to perform water changes at the top of my injection phase).

So 900ml of carbonated mineral water (coke level gassy) added per 25L water (atmospheric equilibriated) should provide slightly more than 30ppm CO₂.


----------



## Soilwork

I could be wrong here but I suspect one of most important aspects of success for this type of co2 delivery is concentration gradients.  It would seem that the rate it which this chamber diffuses in to the water column will be mostly dependent on concentration gradients created by plant uptake.  Thus the more plant mass the faster the chamber is emptied.  It seems like a good way to keep co2 relatively stable in aquaria which is great for ‘programming’ a steady state RuBisCO concentration.  If you notice most of his tanks have minimal surface agitation.  The plants seem to take what they’re using.  My concern would be night time and lack of oxygen.


----------



## dcurzon

I've just gone and cut a 500ml coke bottle in half, made a small drill hole and pushed a sucker through, and attached low inside a 12l tank (no livestock), and fed a pipe from a quickly mixed diy co2 into the chamber.  Not expecting the co2 to start dispersing until tomorrow AM, but will see what happens.


----------



## sparkyweasel

Soilwork said:


> My concern would be night time and lack of oxygen.


An air pump on a timer could take care of any problem of that nature.


----------



## dcurzon

dcurzon said:


> I've just gone and cut a 500ml coke bottle in half, made a small drill hole and pushed a sucker through, and attached low inside a 12l tank (no livestock), and fed a pipe from a quickly mixed diy co2 into the chamber.  Not expecting the co2 to start dispersing until tomorrow AM, but will see what happens.


So my small half coke bottle... The bottle cap is at the top with the cap on, and pipe leading from co2 into the cap. I've made a hole and put a rubber sicker through, so first test was, would co2 leak out of any gap around the sucker? Fortunately it didn't, and the very basic mix has filled the vessel with co2, so approx 250ml of co2.
The drop checker is at mid green.
The co2 is still being generated, and here's where I run I to problems. As I ran it through the cap, I can't move the pipe to another "bell" to contain more.
So, on the plus side, co2 is being saturated into the water and from the colour I'd have to guess at about 20ppm. Also, it is being stored, so when the DIY co2 stops, there's still a stable supply for however long 250ml of co2 will last for, giving a hopefully decent bracket to mix up some more.

So next idea, when this lot has stopped producing and the bell is getting low, will be to remove the bottle top, run the bare pipe into the bottom of the vessel and fit a balloon instead!  Unless the balloon will be too permeable?
In which case, I'll make a larger bell. Or possibly 2, so when one is full I can move the pipe to the other.


----------



## ScareCrow

I had contemplated using a balloon but I'm not sure if the CO²  generated will reach sufficient pressure to inflate it? It'll be interesting to see if it does work.
My other thought was similar to yours. If you had a rigid pipe in hook shape, you could feed the bell diffuser from the bottom and move it between diffusers as necessary. Possibly another option would be to make two diffusers as you have but join the diffusers at the top with a T connector. Then on the diffuser sides of the T have an air valve so you can open and close the supply to each diffuser independently. I never got around to testing it, so I'd be interested to see how you get on and more than happy to copy your success 😂


----------



## dcurzon

ScareCrow said:


> I had contemplated using a balloon but I'm not sure if the CO²  generated will reach sufficient pressure to inflate it?


Hadn't taken pressure to inflate into consideration... 
Which leads me to... Larger bell volume, either by one larger bell or multiple bells.


----------



## dcurzon

So far (early days), I'm pleased. The last in tank glass diffuser I used in there went the way of the broken glass. So then I shoved a ciggy filter in the end of the tube and that wasn't as bad as you might think it would be!
However, right now, my bubble rate has slowed down to roughly 1 per 3 seconds, and I still have exactly the same surface  contact of co2/water, the bell is still full, and the drop checker the same mid green.

Ludwigia super red is already looking redder than it previously has (could be my imagination, and that the older leaves are a bit algaefied), I have some new lifeless mid stem cuttings thrown in there which could prove a good guage.


----------



## rubadudbdub

dcurzon said:


> I've just gone and cut a 500ml coke bottle in half, made a small drill hole and pushed a sucker through, and attached low inside a 12l tank (no livestock), and fed a pipe from a quickly mixed diy co2 into the chamber.  Not expecting the co2 to start dispersing until tomorrow AM, but will see what happens.


This was exactly how I first experimented with co2.  I placed the plastic cup (in my case) in front of the filter outflow to ensure plenty of flow under the surface.  As the process relies on diffusion the intention was to try to keep the co2 concentration gradient (gas to water) as high as possible by washing co2 enriched water away.  Every once in a while I 'burped' the chamber to empty it of whatever gases were in there so it could refill with pure co2, again to maximise the gradient.  The co2 came from student budget friendly yeast and sugar.  Subjectively I felt plants grew a little better, I could see more oxygen bubbles streaming from the plants. On reflection I cannot say how much was down to the co2.  All plants were easy anyway (hygrophila siamensis, vallis, Ludwiga, limnophila).  I reckon it probably provides a more stable co2 level vs on/off injected co2, albeit, not very elevated. 

I doubt whether collecting more volume of co2 in a balloon will help with this system.  To increase the rate of diffusion you need more gas/water interface surface area or a greater gradient. You cannot increase the co2 side of the latter without pressurising, which is impossible in a vessel with an open bottom. 

Having seen home brew (another sugar/yeast mixture) in glass bottles exploding under pressure, I'm sure you could fill a balloon.  I'm not sure I'd bother though.  Recall what happens when you blow up a balloon and let the neck go. The elastic recoil empties it in seconds. I reckon it'll just rapidly bubble gas out your coke bottle until its empty.   I'd keep it simple for the time being and see how your plants react.


----------



## Snowstreams

michaelc said:


> I saw the same you tube video made by Cory form Aquarium Co-op. Watching it made me finally make up my mind to go for a Tropica type Aerosol CO2 set up.


3 years later and Aquarium coop just released a new video of that same shop this week. 
Its amazing how soluble co2 is from looking through this thread. 
Anyway I was thinking it might be a great cheap co2 system for my fluval chi too. 


michaelc said:


> .......
> The difference CO2 made to my plants in my Fluval Chi was remarkable. .....


What system did you get to fit into a chi? 
Mine is only 17 litres so space is tight.


----------



## Maf 2500

Snowstreams said:


> 3 years later and Aquarium coop just released a new video of that same shop this week.


I saw that video too - the shop owner is an amazing guy, great to hear his history and how he came to San Fran and ended up starting the shop and making it work in what seems to be a less affluent part of the city.

Link to the new (Dec 2021) video

Edit: Also worth quoting the pinned comment from under the video:


> Note from the editor : Sincerely, thank you for stopping by and watching this interview. Being an immigrant myself, I really wanted to display his wonderful story for you to see. Hope, it was worth the wait. Happy Holidays to you and your family and I’m sure I can speak for the crew at Aquarium Co-op when I say.. “Thank you for your many years of support, we appreciate every bit of it.” Edit : it’s only been 2 hours since this has been released and reading your comments brought tears to my eyes. This is really gonna make my week, let alone Justin’s day. Thanks again


----------



## erwin123

Great video and nice idea. Is this is how the idea works? I collect CO2 from my high tech tank diffuser, plug up the test tube, and bring it over to my low tech tank?

I need to rig something to allow the entire test tube to be submerged in the tank but this will do for now. 

 This is in my 16 litre low tech so even a small amount of CO2 should have some impact?


----------



## ScareCrow

erwin123 said:


> Is this is how the idea works? I collect CO2 from my high tech tank diffuser, plug up the test tube, and bring it over to my low tech tank?


Yeah that'll work. The small diameter of the test tube will restrict the amount of diffusion you get though as there's only a small surface area between the CO² and the water.


----------



## arcturus

ScareCrow said:


> Yeah that'll work. The small diameter of the test tube will restrict the amount of diffusion you get though as there's only a small surface area between the CO² and the water


Aren't we reinventing the wheel here? You have built a basic reactor and the video shows nothing new. If the goal is to maximize CO2 dissolution and control the injection rate, then simply discard the diffuser and replace it with a proper CO2 reactor...


----------



## AlecF

erwin123 said:


> View attachment 178519 View attachment 178520
> Great video and nice idea. Is this is how the idea works? I collect CO2 from my high tech tank diffuser, plug up the test tube, and bring it over to my low tech tank?
> 
> I need to rig something to allow the entire test tube to be submerged in the tank but this will do for now.
> 
> This is in my 16 litre low tech so even a small amount of CO2 should have some impact?


I love to imagine a series of smaller tanks, and smaller receptacles, each receiving a smaller dose of CO2.


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## ScareCrow

arcturus said:


> Aren't we reinventing the wheel here? You have built a basic reactor and the video shows nothing new. If the goal is to maximize CO2 dissolution and control the injection rate, then simply discard the diffuser and replace it with a proper CO2 reactor...


Not so much reinventing the wheel as going back to before the wheel was invented. This was how it was done before all the diffusers reactors etc were available in the hobby. As you say it's far from the most efficient way of doing it. All I was getting at was that the idea of a bell diffuser is to dissolve the trapped CO² into the water. A test tube has a very small diameter and therefore the surface area between the trapped CO² and water is going to be very small, making it less efficient than it already is. 
I believe he uses bell diffuser in the video out of cost/ease of setup. He doesn't have to have multiple manifolds/regs/cylinders/lines just a few bell diffusers and fill them up manually when he does other daily maintenance.
If @erwin123 wants to use a bell diffuser it's up to them.


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## erwin123

In the space of a few hours, it seems that most of the CO2 has been transferred to the tank, as shown by the water level in the test tube being higher than the water level of the tank?


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## arcturus

ScareCrow said:


> Not so much reinventing the wheel as going back to before the wheel was invented. This was how it was done before all the diffusers reactors etc were available in the hobby. As you say it's far from the most efficient way of doing it. All I was getting at was that the idea of a bell diffuser is to dissolve the trapped CO² into the water. A test tube has a very small diameter and therefore the surface area between the trapped CO² and water is going to be very small, making it less efficient than it already is.
> I believe he uses bell diffuser in the video out of cost/ease of setup. He doesn't have to have multiple manifolds/regs/cylinders/lines just a few bell diffusers and fill them up manually when he does other daily maintenance.
> If @erwin123 wants to use a bell diffuser it's up to them.



 But in the video, the bell was used as a CO2 container. There was no CO2 injection at all. This is a old school way of providing CO2 to avoid all the CO2 equipment.

But in this case we are using a pressurized CO2 system that is continually injecting CO2 into the tube/bell. So, we are using the bell not as a CO2 container but as an (inefficient) reactor! And that is the part that does not make sense.. either you fill in the container with CO2 once in a while (like shown in the video) and skip the CO2 regulators, solenoids, etc., or you properly use pressurized CO2 injection...


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## ScareCrow

@arcturus I think you've missed the bit below. He's filling the tube and taking it to another tank. So not using it as a reactor.



erwin123 said:


> I collect CO2 from my high tech tank diffuser, plug up the test tube, and bring it over to my low tech tank?


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## arcturus

ScareCrow said:


> @arcturus I think you've missed the bit below. He's filling the tube and taking it to another tank. So not using it as a reactor.


Yes, I did! Now the setup makes sense. Thanks for the correction.


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## Platangel

zozo said:


> starting at 3 pm day before and this is 8 am next day
> 
> pH 7.7 and a nearly co2 empty bottle in 17 hours.
> View attachment 116640
> 
> Seems a rather effective method, is it because of the vacuum? I expected it to last several days as stated in the video.Completely underestimated it..
> Lets fill it up again..


How are you holding that bottle there in place?


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## zozo

Platangel said:


> How are you holding that bottle there in place?



Drilled 3 small holes @ 90°, 10mm under the bottle top rim and put in suction cups, then the bottle upside down in the corner... 
The black ones as seen in the picture...


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