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Old school co2 method.

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.
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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.. :thumbup:
 
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.
 
akwarium said:
2% of the total surface area to get a CO2 level of 30 ppm
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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.
 
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.
 
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.
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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.

recent_mauna_loa_co2.jpg
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.
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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
 
Just thinking out loud here but has anyone checked the amount of CO2 in sparkling water from the supermarket? 🙂
 
Aqua sobriquet said:
Just thinking out loud here but has anyone checked the amount of CO2 in sparkling water from the supermarket? 🙂
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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.
 
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.
 
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.
 
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.
 
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.
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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.IMG_20201120_232224.jpgIMG_20201120_232209.jpg
 
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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 😂
 
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.
 
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.
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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.
 
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.
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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. .....
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What system did you get to fit into a chi?
Mine is only 17 litres so space is tight.
 
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