# Co2 and light timing



## Franks (5 Jul 2016)

Today I had time to monitor hourly the pH of the tank so I could perfect the light on time at the 1 pH point drop. I was surprised to see that even with a guesstimate 2 hour Co2 on prelight period, I still wasn't dropping enough pH.   

Tank is 155 litres with loads of flow and surface agitation. Equally,  I cut Co2 one hour before lights out but I only lose around 0.3pH.  

It seems no one loads up on Co2 for three hours before lights on but I'm thinking I'll need to. I also think I can afford to cut Co2 two hours before lights out as it takes so long to dissipate anyway. Ultimately, it's just going to be a shift in the cycle. 

Everyone seems to just do an hour before lights on but then everyone also seems to run 20 litre nanos toowhuch I guess dissolve much more quickly.

Do any larger tank owners notice a similar trend in their regime?

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## Andy Thurston (5 Jul 2016)

Franks said:


> Tank is 155 litres with loads of flow and surface agitation


CO2 injection is a balancing act if you have loads of surface agitation then this will remove co2 from the water coloumn. you might want to reduce this a little bit to see if you can keep more co2 in the tank thus reducing the time it takes to reach the 1 point drop.
Injection rate, surface agitation and timing are the 3 variables you will need to adjust to get the balance right.
Also remember if there is livestock in the tank, when you make adjustments to the co2, you will need to be around to monitor it and make sure you don't add too much. If you do add to much co2 then you will need to remove it before it harms/kills your critters, this can be done by using an airstone or doing a large waterchange


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## AquaPlantDemon (6 Jul 2016)

It takes a little while after lights on for plants to wake up and start uptaking nutrients (including CO2) so it's not essential to reach max concentration before lights on. Hobbyists have different views on this, some will always advocate for max CO2 concentration prior to lights but I haven't found it necessary. I tried the max concentration before photoperiod by having CO2 on 3hrs before and didn't notice any difference. 

I use a diffuser which isn't the best method for CO2 addition, a reactor would be better. Given this I run my CO2 2 hours before the photoperiod at the moment. My tank reaches max concentration (estimated ~30ppm) around 1 hour into the photoperiod. A reactor should reach this concentration much faster.


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## John S (6 Jul 2016)

There are people on here who start the CO2 three hours before lights.


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## Paulo Soares (6 Jul 2016)

John S said:


> There are people on here who start the CO2 three hours before lights.



It all depends on the injection rate. Even In the past i used to have it runniing 24 hours. No harm done. 

I have it running three hours before lights up and shuting down two hours before lights off. I do this cause i prefer a more slower injection for the same objective than a faster injection. 

In a faster injection you are altering all water chemistry very faster and i do believe that this has greater impacts on live stock as in the water and consequent effects on plants. 

In nature we do not have a swicth right? CO2 is always present. 

That´s my point of vyew. 

Don´t forget as recommended to be at home when altering CO2 injection. 



> Today I had time to monitor hourly the pH of the tank so I could perfect the light on time at the 1 pH point drop. I was surprised to see that even with a guesstimate 2 hour Co2 on prelight period, I still wasn't dropping enough pH.



As for this kind of measuring, simply forget it. It is not a reliable method and was desmistified a long ago, but as you know things are not erased from the web even when it is proved that they are very wrong. The only and the best is the Drop Cheker. 


Big hug to all.


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## DavidW (6 Jul 2016)

After a few power cuts etc the timer on my lights went completely out of sync with the timer on my CO2, this was my fault because I always put the timer right on the light but forgot about the CO2, anyway I think it ended up being 4 hours apart I only realised what had happened after I developed a massive hair algae issue. Now I've got the lights and CO2 back to 1 hour apart and done allot of pruning to get rid of lots of the algae everything is back under control. I also got 6 oto's to help with the problem.

SO if you looking at adjusting to 3 hours apart keep an eye out for any signs of increased algae growth.


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## Franks (6 Jul 2016)

Thanks guys. 
Seems odd to be reliant on just the DC as these are so far behind the true parameters. There's also the accuracy of the colour to gauge too. I bet you couldn't see a 0.3ph difference through DC colour change.  The PH pen gives instant results.  


Regarding the power cut, which way out was the gas timing - coming on 4 hours late or 4 hours early?

I think my tank takes a long time to fill up with Co2 and equally, it takes much longer than an hour for the pH to start returning. I'll see how it reacts to the current shift in Co2 timing. 

Thanks 





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## Andy Thurston (6 Jul 2016)

Paulo Soares said:


> As for this kind of measuring, simply forget it. It is not a reliable method and was desmistified a long ago, but as you know things are not erased from the web even when it is proved that they are very wrong.



If this is such bad advice then why are 70% of co2 users on this forum using it?



Paulo Soares said:


> The only and the best is the Drop Cheker.



This is so untrue! What is good for one person does not make it the only and best way. If the truth be known it is the only way to measure the co2 concentration accurately but drop checkers are notorious for having a delay, that delay can be anything from 1/2 a hour to 3 hours depending on the drop checker and the solution used, so in my opinion you should use a d.c. to check the amount of co2 in the tank and use your ph pen to check the timing of the co2.

In my opinion, from what the OP had written it seemed that they were doing a fairly good job of finding their way with co2 injection and I didn't want to go into massive detail and end up confusing them.

Finally Paulo, I have read many of your posts and to be quite frank lots of them have been misleading. Remember many people on the forums are relatively new to co2 and offering different methods all at once can be very confusing to a beginner, often leading to failure and putting them off the hobby. Please be patient and allow people to try one thing at a time and see what happens, then if they are still having problems then offer them a different approach.


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## Paulo Soares (7 Jul 2016)

Big clown said:


> If this is such bad advice then why are 70% of co2 users on this forum using it?



Check Tom Barr report and you´ll find all explanations on this matter. There´s a topic of it. 
And even on this forum the user Ceg also explains why that method is not a reliable one. I´m not inventing. And i also try it at home and never worked. So instead of him loosing time on this why not recomend DC method? 
Why let a begginer (using your words) lose patient and time and money trying things that the specialists of this Hobby have proven to be wrong? 



> This is so untrue! What is good for one person does not make it the only and best way. If the truth be known it is the only way to measure the co2 concentration accurately but drop checkers are notorious for having a delay, that delay can be anything from 1/2 a hour to 3 hours depending on the drop checker and the solution used, so in my opinion you should use a d.c. to check the amount of co2 in the tank and use your ph pen to check the timing of the co2.



As you can read i said that it all depends on the Injection rate! 
OF course the reagent has a delay. It´s a matter of the begginer to watch and improve. If by the time lights went on the reagent is allready green than you know that you have Co2. 
Suposed your lights went on at 15 PM. If by 14 PM your drop checker is allready green than you know that you´re injecting (injection rate) too much or you can reprogram the timer to star injecting one hour later. 

And even if for instance at 16 Pm the drop checker is yellow he will know that it is injecting too much. Again : injection rate. 

This is not a walk in park but it´s not also that dificult to balance. 

I didn´t mention any reagent but he can buy the CAL AQua reagent. It´s allready calibrated in 30PPM.. that easy...

hugs to all


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## John S (7 Jul 2016)

Paulo, Ceg has always advocated using a PH meter to generate a profile.


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## Paulo Soares (7 Jul 2016)

By the way.. i do also read you. But i never state that you are "misleading". 
You know why? Cause I do understand (you don´t need to tell me) that when you coment or quote something that you are giving your point of view based on your own experience and others. No one is the God of thruth. 

Good sense is needed when we are simply reading and not hearing the voice  

Quoting you: 



> "i had a tank which always had a green dc when lights were off and yellow when lights were on. it can become a problem overnight because plants and fish produce co2 at night and co2 levels could rise to toxic levels. if this happens then an airstone can be used to remove the excess co2 at night time"



And that is one good reason for using Drop Checker and not PH method. But than again is my humble opinion. 

Best regards


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## Paulo Soares (7 Jul 2016)

John S said:


> Paulo, Ceg has always advocated using a PH meter to generate a profile.



I´ll try to find that Thread. Many thanks John


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## Paulo Soares (7 Jul 2016)

From Barr Report:



> *CO2/pH/KH table*
> 02-15-2013, 06:04 AM
> 
> Please ignore the* recommended ranges for good/Bad CO2 ppm*, they vary by tank and lighting and other factors, a good range to target initially is 30-40 ppm.
> Then adjust slowly watching plant health and vigor.



http://www.barrreport.com/forum/barr-report/co2-enrichment/11862-co2-ph-kh-table


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## DavidW (7 Jul 2016)

It was coming on 4 hours too early


Franks said:


> Regarding the power cut, which way out was the gas timing - coming on 4 hours late or 4 hours early?


4 hours early so it was on while the lights were off.


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## AquaPlantDemon (7 Jul 2016)

Isn't a drop checker a pH test essentially?

OP: Do your lights take time to ramp up to full intensity, or come on at 100%? I ask because this can affect plant uptake of CO2 also.


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## Franks (7 Jul 2016)

They are just on/off T5HO 6700k bulbs. I do have an hour of very dim led lights prior to T5's though. I've been reading and actually want to test a method of cutting the wavemaker during the day and running it only at night. I would think this would build Co2 much more quickly too. Dissipation through the night with the wavemaker on and also clearing any detrius from the day. The tank is much more pretty and natural when the plants aren't being blown around. 

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## Franks (7 Jul 2016)

And yes, the DC is effectively a ph measuring tool. Its made with a ph agent afterall.  The instant results of a pen are much more ideal to tune light staging. Afterall, the DC might be 2 hours behind. If it's lime green when lights are just turning on,then you probably had enough gas an hour before when I was turning an off-blue colour?

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## Andy Thurston (7 Jul 2016)

I am familiar with all the articles that you are quoting both here and on the Barr report and I'm not sure if you fully understand them or your poor english language skills are making your posts appear confusing. Judging by your reaction to my post you have misunderstood that too. I said in the following quote that drop checkers were the only way to measure co2 accurately


Big clown said:


> If the truth be known it is the only way to measure the co2 concentration accurately but drop checkers are notorious for having a delay, that delay can be anything from 1/2 a hour to 3 hours depending on the drop checker and the solution used, so in my opinion you should use a d.c. to check the amount of co2 in the tank and use your ph pen to check the timing of the co2.


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## Bolota (7 Jul 2016)

Paulo Soares said:


> From Barr Report:
> 
> 
> 
> http://www.barrreport.com/forum/barr-report/co2-enrichment/11862-co2-ph-kh-table




I read that post and I don't see a criticism on the method (just see the post that follows where they use the same table for different considerations). He just says we should ignore the good-bad ranges that usually go with those tables... Isn't that right?


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## Andy Thurston (7 Jul 2016)

Franks said:


> And yes, the DC is effectively a ph measuring tool. Its made with a ph agent afterall.  The instant results of a pen are much more ideal to tune light staging. Afterall, the DC might be 2 hours behind. If it's lime green when lights are just turning on,then you probably had enough gas an hour before when I was turning an off-blue colour?
> 
> Sent from my E5823 using Tapatalk



Do you have fish/ shrimp in the tank?


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## Franks (7 Jul 2016)

Yes I have a few Amano shrimp and harlequin, gourami and cardinals. All display no stress during Co2 injection. I'm now playing with surface agitation and may even play with running no wavemaker during lights - just the filter spraybar.  At night, I'd run the wavemaker facing the surface.  

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## Andy Thurston (7 Jul 2016)

Some people might not agree with this but I'll tell you anyway. Your livestock will be a much better drop checker than any piece of manufactured equipment and the more different types of fish/shrimp that you have the better. Different critters respond differently to co2 levels at different times. ottos will get pink/red gills before the co2 reaches critical levels and glowlight tetras will loose their colour way before co2 reaches critical levels. I removed my drop checker from my tank because it was always yellow.

 When I set a new tank up I have minimal surface movement. I inject co2 as quickly as possible until the livestock starts showing signs of discomfort/distress as soon as this happens I use my ph pen and take a reading, then I do a water change to bring the co2 to safe levels(I also increase surface movement/agitation at this time). This gives me an absolute maximum/minimum ph/co2 level that the livestock can handle. If the reading is 6.2 for example then when I set up my co2 levels then I aim for around 6.4-6.5 at lights on and throughout the photoperiod. 

Have a read through my journal(it might not be the best scaped tank but the technical side of things are covered quite well) there are some good pictures of fish showing the early signs of co2 distress there is also a ph profile for the tank which will give you an idea of what you are aiming for although your ph and KH values will be different. I went through many problems with the tank and every change I made is documented there.
here is the link

http://www.ukaps.org/forum/threads/andys-60l-cube.31194/

any questions, feel free to ask


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## Franks (8 Jul 2016)

Thanks for the advice, I'll have a read through your journal. 

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## Easternlethal (8 Jul 2016)

I agree the best approach is actually to look at your fish to find out what is the real max Co2 your tank can hold. However it's not a good idea to reduce flow because that actually helps distribute Co2 around the tank. Without it the dissolved Co2 molecules will disperse upwards and out of the tank. some of course will eventually spread through diffusion but there's no reason to rely on that. I would also have some surface agitation because it will decrease the level of Co2 at the upper layers of the water column and the more sensitive fish can stay up there if they get uncomfortable. That way you can actually have more Co2 concentration in the lower layers of the water.

Re ph I do not measure either because that actually measures the presence of carbonic acid and is affected by the amount of kh in your tank. If your tank has high kh it will take a lot to drop the ph. Also I don't personally believe carbonic acid is an accurate indicator of the amount of dissolved Co2 in the tank (especially not in a tank with lots of flow under injection that is not in equilibrium).


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## Daveslaney (8 Jul 2016)

Not trying to fuel a fire or anything. Just looking for answers. 
But will not higher surface agitation increase o2 levels? With higher o2 levels can you not run higher co2 levels without distressing your livestock?
Is this why wet dry filters in sumps work so well and allow higher co2 levels to be run? O2 must be high with this filtration method 
If ph pens and drop checkers work on ph readings to monitor co2 levels. Why is a ph controller a unreliable way to regulate your co2 levels?


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## Easternlethal (8 Jul 2016)

higher o2 doesn't mean you can have more co2. they are independent. and o2 should be coming from the plants really. not through the surface. 
my post above explains why ph is not a good measure of actual co2. a ph controller has the same issue.


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## Daveslaney (8 Jul 2016)

Ok thanks. 
When I first started running co2 injection all my returns where underwater so little or no surface agitation. If I pushed co2 levels and my drop checker went into the yellow my fish would be at the surface. 
Now I run the spray bar method so lots of surface agitation so higher o2 levels? Now my drop checker will go into the yellow if I push co2 levels with no apparent distress to my fish. Even though both are independent it suggests to me higher o2 allows higher co2 levels?


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## Franks (8 Jul 2016)

I think I'm at the point where I've reached a safe max. DC is green/yellow tinted,  I'm dropping around 1.2 PH and I've a large spraybar and wavemaker running. No distress to fish whatsoever and all plants apart for my shaded anubus pearl nicely when in the last quarter of the photoperiod.  

I think a trip to The Abyss is in order for some more Amano to help munch the slight BBA I get on the wood. 

Cheers guys 

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## Andy Thurston (8 Jul 2016)

Easternlethal said:


> However it's not a good idea to reduce flow because that actually helps distribute Co2 around the tank


please re read my posts. I was not recommending that the op reduced their flow. I was recommending that the op reduced the surface aggitation to keep more co2 in the tank to obtain a maximum co2 level for their livestock


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## Andy Thurston (8 Jul 2016)

Daveslaney said:


> Even though both are independent it suggests to me higher o2 allows higher co2 levels?


I believe that this is true too. I also believe that you need to maximize co2 and o2 levels when injecting co2 into your planted aquarium.

I also believe that you should maximize co2 levels without distressing your livestock. if any of your fish have gills that are redder than normal or start gasping at the surface then you should aim for less co2 in your tank (higher Ph). Then if your plants are still suffering then you should consider lowering your lighting levels


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## Easternlethal (9 Jul 2016)

Big clown said:


> I was not recommending that the op reduced their flow.


I didn't say you did. I was responding to the OP's point about cutting the wavemaker during the day.



Franks said:


> I'm dropping around 1.2 PH... No distress to fish whatsoever and all plants


This supports my point that you can have low ph due to high carbonic acid but dissolved co2 is also actually lower than what would be assumed under equilibrium conditions. This is why many aquarists have said that Co2 is frequently lower than what a yellow dropchecker would suggest.



Daveslaney said:


> Even though both are independent it suggests to me higher o2 allows higher co2 levels?


Respiration is not just about getting o2 into the respiratory system but also getting co2 out of the respiratory system. When co2 is high, it makes it difficult for fish gills to remove co2. O2 does not help that. When co2 is increased but so is surface agitation and flow and fish seem unaffected what is happening is that the co2 is being distributed more efficiently and escaping at a faster rate in such a way that the concentration of dissolved co2 actually does not rise overall. And this environment helps plants.


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## X3NiTH (9 Jul 2016)

For 30ppm CO₂ (or thereabouts) drop checker colour states can differ depending on which pH indicating fluid is used, if we stick to Bromothymol Blue, this I have found comes in two flavours, Protonated and De-Protonated. One is an acid the other is alkaline. One fluid will appear red in the bottle but is actually stains yellow (a bit like saffron), the other fluid will be a dark blue in the bottle and will stain a lighter blue.

The two Drop Checkers on the left below were pulled from a CO₂ injected tank and immediately photographed before any colour change could happen at the gas transfer interface.



Same reference 4dKH fluid is used for all checkers, the Yellow reading DC on the immediate left is the Protonated Yellow checker fluid, the one to its immediate right is the De-Protonated checker fluid. The DC on the far right is Protonated checker fluid after going into the reference fluid and not exposed to injected CO₂ in the tank.

It is what it is. I was confused and surprised by this and had to go and read up on indicator fluids a little, thats when I found out Bromo exists in the two flavours. They nearly match in indication but the Protonated form turns yellow earlier under the same concentration of CO₂ than the De-Protonated form does. 

If you have yellow type DC fluid aim for a Yellow DC for 30ppm (or thereabouts), unfortunately on its own there's no way to indicate if the CO₂ is more than 30ppm and climbing unless you have fish to tell you by heading for the surface to breathe.

If you have the blue type fluid you want it to turn the above shade of green to show 30ppm, if it turns yellow it's more than 30ppm (from experience fish will be at the surface above this level of CO₂, different story though if the plants are having a good day and they are pearling due to photosynthesis).


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## Daveslaney (9 Jul 2016)

Ok thanks.


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## herezor (13 Jul 2016)

I would keep surface agitation high and increase CO2 injection. To do that, I have suggested this in a couple of threads, I would buy a cheap permanent pH meter which you can find for 30-40 euros and I would aim for 1 unit pH drop from CO2 on to lights on. Normally you can achieve that with a inline atomizer in 1-2h.

DC, CO2/KH table, bubble counters etc are, in my experience, useless and I must admit I have used all of them in the past.

Just my two cents.


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