# 96 ppm of CO2, way too much ?



## eminor (9 Nov 2021)

Hello, i did a ph profile, to reduce the ph 1 point i have to reach 96 ppm of co2, is it safe ?

the fish and shrimp seems to be ok, plant are growing, nothing crazy though

KH : 6, Ph : 6.5 at light start, drop color: lime green at start, yellow then :/

thx


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## Gorillastomp (9 Nov 2021)

You need to do a 1 PH drop from your degassed tank water. You need to take a sample from your aquarium in a bowl and let it sit for 24 hrs then test the PH. This will be your starting point for the 1 PH drop.



eminor said:


> the fish and shrimp seems to be ok, plant are growing, nothing crazy though


This is unlikely you have reached 96 ppm.



eminor said:


> KH : 6, Ph : 6.5 at light start, drop color: lime green at start, yellow then :/


Would need to know the PH before the injection of the co2. Give us a bit more explanations on how you are injecting your co2 (time it start, when light comes up etc.)


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## Zeus. (9 Nov 2021)

eminor said:


> drop color: lime green at start, yellow then :/


Been there done that  fish gasping and snails all at top of tank. Although I did for some time run tank with DC light yellow, it does carry risks as the slightest change and the [CO2] could be fatal

Like @Gorillastomp said need to use a glass of tank water and let it stand 24hrs or until the pH of it stops increasing.

Have you done a pH profile? pH should be stable from lights on till CO2 off - I personally call stable less than 0.1pH change


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## eminor (9 Nov 2021)

Gorillastomp said:


> You need to do a 1 PH drop from your degassed tank water. You need to take a sample from your aquarium in a bowl and let it sit for 24 hrs then test the PH. This will be your starting point for the 1 PH drop.
> 
> 
> This is unlikely you have reached 96 ppm.
> ...


ph before light, 7.3 7.4

i use ceramic diffuser to the inlet, goes through canister filter, the filter make some noise with bubbles time to time, fine bubble get though the outlet. The spray bar is near 5cm below the top, the hemianthus cuba is growing but slowly which is an indicator of bad co2, every plant is moving calmly


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## eminor (9 Nov 2021)

Zeus. said:


> Been there done that  fish gasping and snails all at top of tank. Although I did for some time run tank with DC light yellow, it does carry risks as the slightest change and the [CO2] could be fatal
> 
> Like @Gorillastomp said need to use a glass of tank water and let it stand 24hrs or until the pH of it stops increasing.
> 
> Have you done a pH profile? pH should be stable from lights on till CO2 off - I personally call stable less than 0.1pH change



it's definetly not stable here, or at least the drop color is changing


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## X3NiTH (9 Nov 2021)

Zeus. said:


> Like @Gorillastomp said need to use a glass of tank water and let it stand 24hrs or until the pH of it stops increasing.



There’s a quicker way to do this and that’s to draw the sample and put it in a lidded container and shake the bejeezus out of it for a couple minutes or so and periodically exposing the sample to ambient air, you can then test the pH with a pH Pen or a dip strip. 

If using a colour indicating titration test kit I draw the sample then add the indicator fluid, I take the reading for current pH and then as above put the lid on and shake the beejeezus out of it (periodically exposing to the ambient air to offgas the co2 that’s been agitated out of the sample) until the colour stops changing, take the measurement and this is your equilibriated reading. I like doing it this way because you can see the colour change happen quite quickly and your not left guessing ‘did I shake it enough?’.


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## Gorillastomp (9 Nov 2021)

eminor said:


> ph before light, 7.3 7.4


Assuming this is your degassed PH, you will need to be around 6.4 or a bit more when lights go on, then it needs to stay around that PH the whole photoperiod.

So i would just adjust the injection rate to get that 6.4 PH stable through the photoperiod. Once you reach the stable PH, adjust the time when your co2 start so you get that PH around 30 min before the lights go on.


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## erwin123 (10 Nov 2021)

achieving pH stability is tricky. Initially I managed a 1.0-1.1 drop.  (i.e. 0.1 variance)

I am now trying to tune for a 1.1-1.2 drop but I've found its not as simple as increasing the number of bubbles per second. Currently, I am at 1.1-1.3 (i.e. 0.2 variance). So I am trying to get it down to a 0.1 variance.

I have a Lily pipe surface skimmer so I am experimenting with changing the skimming intensity to see if it helps.


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## Sdogg (10 Nov 2021)

Why don't more people use PH controllers?

Mine holds target PH within +or- 0.03. So "super stable" by your measure.

Also no need to endlessly fiddle with the stupid needle valve, wack it wide open and the controller does the rest....


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## foxfish (10 Nov 2021)

Perhaps PH controllers have improved in recent years but previously  they have not been popular, very few people use them as they do not offer a continuous  supply  but come on it fits and starts.
Also when they first come on they can fire in a lot of gas that can effect finely tuned reactors but honestly I have not used one for many years.
Besides that many folk dont want extra expense and equipment to monitor and check as the standard tried and tested method works very well once set up.
However please tell us more about your controller and you experience with it especially if your plants are flourishing .


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## Wolf6 (10 Nov 2021)

There is no absolute 'need' to aim for the 'divine' 30mg/l / 1 ph drop, you can choose to go lower, just keep it consistent. I use aqua rebell 20mg/l co2 fluid and make sure that that is lime green on lights on, and as long as its not bright yellow by the end of the day, its all fine. I dont touch the CO2 after having set it at the start, I just keep plant mass in check. I've had my tank running like this for over a year with little/no algae this way (only time algae showed up was when CO2 ran out and I didnt notice and when I switched diffusor and had to re-dial in co2). Fish seem more active and I feel there is a lot more room for error without gassing fish.


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## erwin123 (10 Nov 2021)

Wolf6 said:


> There is no absolute 'need' to aim for the 'divine' 30mg/l / 1 ph drop, you can choose to go lower, just keep it consistent. I use aqua rebell 20mg/l co2 fluid and make sure that that is lime green on lights on, and as long as its not bright yellow by the end of the day, its all fine. I dont touch the CO2 after having set it at the start, I just keep plant mass in check. I've had my tank running like this for over a year with little/no algae this way (only time algae showed up was when CO2 ran out and I didnt notice and when I switched diffusor and had to re-dial in co2). Fish seem more active and I feel there is a lot more room for error without gassing fish.


if you are tuning Co2 for the first time, I guess 1.0 drop is a good target - if you overshoot, you may hit 1.1, 1.2 which is still safe.  If you aim for a 1.2 target straightaway, you may overshoot to 1.3, 1.4 which is starting to get risky, depending on the species of shrimp/fish in the tank, and overall O2 levels.


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## eminor (10 Nov 2021)

if i reduce the temperature of the tank from 25 to 22, co2 will offgase slower right ? will it be easier to use it ?


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## Zeus. (10 Nov 2021)

Sdogg said:


> Why don't more people use PH controllers?
> 
> Mine holds target PH within +or- 0.03. So "super stable" by your measure.
> 
> Also no need to endlessly fiddle with the stupid needle valve, wack it wide open and the controller does the rest....


Used one and found it OK, although there was a peak and dip in the pH from the controller, also using CO2 reactors there is a lag in the pH change as went the CO2 goes off until all the CO2 in the rector is taken up the pH can still change. So I found it far from stable. I find your 0.06 drift which rounds up to 0.1 in my book impressive for a pH Controller . Also the other issue is the pH probe itself needs regular calibration over time so you can think your hitting your target and you may not. 
I find setting the injection rates manually a more stable option and have more confidence in it. 
Also with my duel injection and high injection rates there isnt much room for error, having a PLC doing the timing gives the edge IMO/IME

I have yet to come across another who has been able to drop a 1.3+pH in less than 30mins in a 500L tank and then stable for rest of CO2 period


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## Gorillastomp (10 Nov 2021)

Zeus. said:


> I have yet to come across another who has been able to drop a 1.3+pH in less than 30mins in a 500L tank and then stable for rest of CO2 period


That is none the less impressive. I found out from experience that when you have more turn over for the co2 loop, you can achieve lower PH quicker. Downside for this you will need greater degassing to stabilize the ph drop. 

For my 240 US gallons tank, i can achieve 1.2+PH drop under 40 min and keep it there. I could do greater but it tends to keep lowering the PH through the photoperiod if i increase the injection rate too much (It means my degassing is too low for the injection rate).

IMO the quicker you get the PH drop, the most stable CO2 will be during the photoperiod.


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## Gorillastomp (10 Nov 2021)

eminor said:


> if i reduce the temperature of the tank from 25 to 22, co2 will offgase slower right ? will it be easier to use it ?


Always go the lowest temperature your Fish and Plant can handle to be healthy. The higher the temperature, the plant have to metabolize faster creating more organic waste then more prone to algae, deficiency, etc. 

So yes, at lower temperature you will need less co2,ferts, etc. It will be easier to set.


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## Sdogg (10 Nov 2021)

Fair enough. I check my probe monthly and it's never more than 0.02 out of calibration.

I can't fault mine, solved all the problems I had instantly. So nice having a number to go by and not trying to guess a shade of green


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## Zeus. (11 Nov 2021)

Gorillastomp said:


> That is none the less impressive. I found out from experience that when you have more turn over for the co2 loop, you can achieve lower PH quicker. Downside for this you will need greater degassing to stabilize the ph drop.


Well I do cheat in a way with duel injection, timers, which also make controlling the [CO2] easy also.
*steps*
A. Use one injection and adjust injection rate till you have a stable pH/[CO2] for lighting period allowing for it reaching it peak
B. Use both injections, with second injector open full bore to drop pH/[CO2] and just time how long it takes to hit target pH/[CO2]. I did use the pH controller and PLC for this as a programmed the PLC to recorded the time it took using the off signal from the pH controller.

Both steps are done together to get the pH drop. If tanks pH continues to drop after lights on I just dial down the working pressure on duel stage reg. Then it takes longer to drop pH but PLC records how long it took to reach target pH then adjust PLC timings to suit - Visa versa if pH raises


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## Gorillastomp (11 Nov 2021)

Zeus. said:


> A. Use one injection and adjust injection rate till you have a stable pH/[CO2] for lighting period allowing for it reaching it peak
> B. Use both injections, with second injector open full bore to drop pH/[CO2] and just time how long it takes to hit target pH/[CO2]. I did use the pH controller and PLC for this as a programmed the PLC to recorded the time it took using the off signal from the pH controller.


This make sense and is probably a more efficient way of doing it. You are loading up the water with carbon before light on then keep what is used up with the single injection. I think this is doable without a PLC, just need to configure the second injection point while you are around then you can manage it with a timer.


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## Zeus. (12 Nov 2021)

Gorillastomp said:


> This make sense and is probably a more efficient way of doing it. You are loading up the water with carbon before light on then keep what is used up with the single injection. I think this is doable without a PLC, just need to configure the second injection point while you are around then you can manage it with a timer.



Ignoring the cost its self as a down side, the main issue is your weaponizing the CO2 injection system, esp if you use very high injection rates. If a timer fails to switch off or you connect the power feed to the wrong solenoid valve by mistake you can wipe out all fish/shrimp/snails in a very short time. A PLC has industrial reliability and a great track recorded, plus with the software on a PC a PLC uses a nice interface to set times esp with @ian_m 'TankyMyTanky' brilliant software design for a timer system. Downside is you will need to learn/understand the GUI for the logic it uses - I found it fun and a great challenge.

So using a twin injection is not for the faint hearted and I would advise *extreme caution* and you do it at your own peril


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## ceg4048 (13 Nov 2021)

eminor said:


> if i reduce the temperature of the tank from 25 to 22, co2 will offgase slower right ?


No. The speed at which the gas escapes is more or less the same. What does change at 22 deg. is that the water will have a higher gas solubility than it does at 25 deg., which is a good thing.


eminor said:


> will it be easier to use it ?


No.

Cheers,


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## ceg4048 (13 Nov 2021)

eminor said:


> Hello, i did a ph profile, to reduce the ph 1 point i have to reach 96 ppm of co2, is it safe ?


Also, you are definitely doing or thinking something fundamentally wrong if you calculated 96ppm. How did you obtain this number?

Cheers,


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## eminor (13 Nov 2021)

ceg4048 said:


> Also, you are definitely doing or thinking something fundamentally wrong if you calculated 96ppm. How did you obtain this number?
> 
> Cheers,


I tested KH and PH and checked co2 chart


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## Zeus. (13 Nov 2021)

eminor said:


> I tested KH and PH and checked co2 chart



I Have only tested my kH once out of interest as son had a kit, after that I just accept what is is and get on with it. Ignore the kH and pH chart it does more harm than good


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## eminor (13 Nov 2021)

Zeus. said:


> I Have only tested my kH once out of interest as son had a kit, after that I just accept what is is and get on with it. Ignore the kH and pH chart it does more harm than good


That's what i'm thinking about, if it was really that high my fish would be on the top


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## ian_m (15 Nov 2021)

eminor said:


> I tested KH and PH and checked co2 chart


This chart is only for pure carbonate hardness and CO2 and not really applicable to a fish tank with all the other salts & water contamination, despite many people attempting to use is, as you clearly have.

Best methods are ignore any test kits, the rubbish bin is an excellent place to store them, and either use a pH pen to try and get 1 unit pH drop between CO2 off and CO2 & lights on or use a drop checker.

My preference is a drop checker as the solution is completely isolated from the tank water this only reads CO2 level. Aim for nice green on drop checker when lights come on and stay green for whole lighting period and you can't go wrong with that.


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