# CO2 tuning - need help



## kilnakorr (28 Mar 2020)

I finally got my setup and flow the way I want it.
I just can't get my CO2 right.
I'm running to large reactors (2.7Liter each) to my 360 Liter tank.
Looking at PH it drops pretty slowly (0.4 after 2 hrs). Bubble rate on both is pretty fast, to fast to count.
Decent surface movement but not breaking it.

I'd like a 1~ish PH drop and go from there, but seems impossible to achieve in 2-3 hours from CO2 on till lights on.

Any ideas on how should I proceed?


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## Zeus. (28 Mar 2020)

Heres my BPS rate on my 500L



But I do have twin injection and one switches off after 1.0pH drop which takes about 30mins

I go though a 6.5Kg CO2 cylinder in about 30days

You might find the CO2 used Database handy


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## kilnakorr (28 Mar 2020)

Thanks @Zeus. 

The database doesn't do me any good right now.



Zeus. said:


> ...one switches off after 1.0pH drop which takes about 30mins



I do have twin injection also, but not possible to switch one off.

I guess I'm wondering (maybe too much) on how most people can get the 1 ph drop in around 2 hours before lights on, and not get an additional drop in ph afterwards.

I find I have 2 options:
1: Start CO2 4-6 hours before lights on to get my 1 ph drop that won't drop much afterwards.

2: Crank the CO2 up, and add ph-controller.

I dislike the controller as CO2 rate will be affected by ph changes in tank.


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## Zeus. (28 Mar 2020)

The way I work it is simple.

1.Work on getting a stable pH first from lights on till CO2 off as the injection rate determines the CO2 concentration throughout the photoperiod for your plants/light/surface agitation, so when the injection rate is correct for your plants/light/surface agitation step one done.

 2. Then you see how long it takes to reach the stable pH once the injection rate is known/set, the time it takes to do it 'is the time it takes' messing with the injection rate to speed up the pH drop keeps making the pH unstable  so back to step one 

This IMO is where most get it wrong, get it stable first, then just time how long it takes. can take weeks/months esp if only got weekends.

If you adjust your CO2 injection rate/BPS go back to step one, then step two.
If you increase light intensity - go back to step one,then step two.
as your plant biomass increases CO2 demand increases so pH becomes unstable- go back to step one,then step two.

Increasing/decreasing your injection rate changes the time it takes to get the pH drop your after, but its the stable pH that we are after and the time it takes to get there is the time it takes 

Having twin injection which can individually switched on and off makes it very easy (I am the only person that I am aware off that does that). Being able to only switch one or more on/off at the same time gives less control so therefore makes it much harder.

I just used one to get it stable. Then timed how long it took to get the pH drop with two and have the seconded one switch off after that time. My seconded injected rate is full open on the needle value.


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## kilnakorr (28 Mar 2020)

So basically crank the CO2 until I get my desired PH and gas/de-gassing is stable.
Then time from CO2 on desired PH is reached, which tells me how long before lights on CO2 must be turned on.

Sounds simple enough

I'm afraid CO2 has to come on several hours before lights on.
Going to start it early tomorrow and see when I hit my desired ph.


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## kilnakorr (29 Mar 2020)

What ph should I aim to reach when injecting Co2?

I took out some tank water last night, and tested this morning.

Degassed water: 8.1
Tank: 7.3
Dropchecker light blue.

So should I aim for a ph of 6.3 to get roughly 30 ppm Co2 in the tank?


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## Zeus. (29 Mar 2020)

kilnakorr said:


> What ph should I aim to reach when injecting Co2?
> 
> I took out some tank water last night, and tested this morning.
> 
> ...



To get the tanks degassed pH I normally tank glass of water and take the pH 24hrs later and use that value. 

(Going off the pH of your glass of water I would say you have very hard water BTW even harder than mine !!! do stones come out in the water when you run the tap  )

you DC is light blue which surgests you have about 8ppm CO2 in your tank at that time.

if you aim for 6.3pH you will be over 30ppm CO2 IMO more like 50-60ppm CO2 and your DC will be yellow to light yellow about 2hrs later.

Dont rush take your time would be my advice, (its not like must of us are in a rush ATM) I would aim for about 6.8pH and see what colour the DC changes if/when you get the pH stable I would trust the colour of the DC atfer 2hrs of maintaing a stable pH as a good/best way of measuring the [CO2]. keep a close eye on your Fish when dropping the pH 

I personally class pH as stable when the pH is within a 0.1pH range. Getting it completely stable isnt needed IMO/IME, but more stable the better

"Keep Safe"


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## kilnakorr (29 Mar 2020)

Thanks @Zeus. 
Tuning in CO2 is really a hazzle with a new setup, since all values are changing (ph,kh etc).



Zeus. said:


> Going off the pH of your glass of water I would say you have very hard water BTW even harder than mine !!! do stones come out in the water when you run the tap  )


I think it is pretty hard, but can't remember th Gh/kh values.

I'm gonna try getting more info on the water.


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## kilnakorr (29 Mar 2020)

Seems a lot of my tests are old, so not reliable.

According to the water supply hardness is 17-18 dH, so fairly hard. KH is 11(test kit).
KH in tank is 5.5.

My PH has dropped to 6.6 in 2 hours. PH/KH relation means I should be at 41 ppm CO2, but I doubt it.


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## Zeus. (29 Mar 2020)

what does your water company say you Ca and Mg ppm are?

I dont use test kits as they arent not reliable at hobby level


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## kilnakorr (29 Mar 2020)

Zeus. said:


> I dont use test kits as they arent not reliable at hobby level


True. Gives a direction but that's it.

Water supply values listed:
Ca. is 127 mg/L
Mg. is 12.5 mg/L


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## Zeus. (29 Mar 2020)

put your ppm into my 'Water Report Wizard'





Also tells you what Mg and Ca youve added with your WC (50% in this case)





(its states my tank size but that irrelevant )


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## kilnakorr (29 Mar 2020)

Guess  the term 'very hard' depends on country then.
Questions is: How does these numbers help me with my CO2?


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## kilnakorr (29 Mar 2020)

PH is 6.5 (4 hrs. after start). Seems to be close to being a stable value.

Took a few pictures of drop checkers (added one to each side of tank).


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## Zeus. (29 Mar 2020)

Thats the DC colour I like and aim for i.e. 30ppm CO2 plus 

adjust the CO2 on time to suit the injection rate for time to get to pH drop (if the pH drop was stable from lights on till CO2 off) - repeat process again tomorrow


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## Zeus. (29 Mar 2020)

kilnakorr said:


> Guess the term 'very hard' depends on country then.



Yes



kilnakorr said:


> Questions is: How does these numbers help me with my CO2?



Doesn't - but with your tap water and a 50% WC your adding about 6-7ppm Mg, so can adjust the amount of MgSO4(H20)7 salt you add to your DIY ferts (if using DIY ferts OFC), dont need to add any Ca as you have plenty


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## kilnakorr (29 Mar 2020)

Zeus. said:


> MgSO4(H20)7 salt you add to your DIY ferts (if using DIY ferts OFC), dont need to add any Ca as you have plenty


True.
I should redo math on my Mg ferts.



Zeus. said:


> I would aim for about 6.8pH and see what colour the DC changes if/when you get the pH stable I would trust the colour of the DC atfer 2hrs of maintaing a stable pH as a good/best way of measuring the [CO2]



You might be right. Aiming for 6.7-6.8 tomorrow


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## milesm (7 Apr 2020)

kilnakorr said:


> What ph should I aim to reach when injecting Co2?
> 
> I took out some tank water last night, and tested this morning.
> 
> ...



you are not getting enough degassing over night if pH is 7.3. my suggestion is to invest and use a surface skimmer or at least try to increase surface agitation.
8.1 is your baseline pH, and i agree with zeus to drop to 6.9 or so. it will take several hours to get there; my co2 comes on 3 hours before the lights. pH remains very stable over the course of the photoperiod. finally, get rid of that drop checker.


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## Zeus. (7 Apr 2020)

milesm said:


> get rid of that drop checker.



I'm a DC fan, therey cheap require little to no maintenance I change the fluid in mine about twice a year, don't need batteries or calibrating, they just work, great for a quick reference check,  Each to there own.

Out of interest @milesm  why did you say to get rid of it?


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## Andrew Butler (7 Apr 2020)

kilnakorr said:


> I do have twin injection also, but not possible to switch one off


can you fit an additonal inline solenoid to one? Unsure how this would effect the other if they were both regulated individually?


kilnakorr said:


> I'm gonna try getting more info on the water


You could always try looking up Triton labs, they are behind what was a 'revolutionary' new way of running a marine aquarium without water changes which worked fine for me but since it first came out it has changed a great deal.
I'm sure the results are not be effected by the fact it's freshwater compared to salt from something they said to me before when I inquired but I never bothered.
If you're that interested have a look over the link and ask them the questions. Link is to their main site and think this is the correct test if it shows all the parameters you want.
https://www.triton-lab.de/en/icp-oes


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## jaypeecee (7 Apr 2020)

Zeus. said:


> I dont use test kits as they arent not reliable at hobby level



All test kits? All parameters? I know that my test kits give sufficiently accurate results. That'll do for me and I suspect would be perfectly acceptable for many other aquarists.

JPC


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## Zeus. (7 Apr 2020)

jaypeecee said:


> All test kits? All parameters? I know that my test kits give sufficiently accurate results. That'll do for me and I suspect would be perfectly acceptable for many other aquarists.
> 
> JPC



Each to their own OFC  

But I embrace T Barrs EI dosing (no need for test kits) fully

However I did test my API test kit last week (had some time on my hands), with RO water, 5ppm NO3, 10ppm NO3 and 50ppm NO3, which I had made up, I must confess that I could see a difference in the range of [NO3] but they did not match the colour chart, they was close but not close enough. I could do with some more test tubes so I can run the tests with reference concentrations then use the colour change as a direct reference to the sample I'm checking.


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## foxfish (7 Apr 2020)

The accuracy of home test kits is a much discussed subject on this forum, not so much of late but certainly two or three years ago, test kits were possibly the most debated theme outside of lighting and C02!
To be honest I never really absorbed  the scientific reasons given but accepted the facts due to the facts being offered, were backed by very confident and experienced people.
As I remember it, most hobby kits are capable of measuring within reasonable limits but are often influenced by other chemicals that might be present in a aquarium.
Or in other words (maybe?) if you had a bucket of pure RO water and added a single element then that element might be detected  quite accurately by the test kit but if you then added several other chemicals then the test results might well be effected and become inaccurate?
I am really not sure if that is a good analogy, maybe someone with a better grasp can explain it better.


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## Zeus. (7 Apr 2020)

foxfish said:


> most hobby kits are capable of measuring within reasonable limits but are often influenced by other chemicals that might be present in a aquarium.



Good point


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## jaypeecee (7 Apr 2020)

foxfish said:


> As I remember it, most hobby kits are capable of measuring within reasonable limits but are often influenced by other chemicals that might be present in a aquarium.



Hi @foxfish 

What you have said is one of the reasons why test kits may give inaccurate results. But, the $64,000 question (my chemistry master's favourite quote) is how inaccurate? Accuracy needs to be quantified. I would rather have a figure with +/-20% accuracy than no figure at all. I don't know of anyone who has done well-controlled scientific experiments to make the assertion that test kits are superfluous. But I'd be the first to sit up and listen to scientific facts. In fact, as I type this, I can think of a possible way. I know two professional chemists, one of whom runs an analytical chemistry laboratory. But I can't afford his prices! But, there is one other option and, dependent on price, I may be prepared to foot the bill.

In the meantime, if anyone knows of any scientifically-conducted test kit reviews, please bring them to our attention.

JPC


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## Zeus. (7 Apr 2020)

jaypeecee said:


> if anyone knows of any scientifically-conducted test kit reviews



Well EI dosing doesn't need such test as the maths fits its purpose, dose in excess and 50% WC resets the tank, ferts are non limiting and toxins are kept with safe limits 

Its only worth doing a test if the result changes the path you would take or when the results take time it may modify the path when you get the results esp in medicine. So if the test are unreliable eg false positives etc treat for the worse case and watch your plants.


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## kilnakorr (11 Apr 2020)

I see the thread has changed subject a bit, so just updating for any future readers.


milesm said:


> you are not getting enough degassing over night if pH is 7.3. my suggestion is to invest and use a surface skimmer or at least try to increase surface agitation.


I have a decent amount of surface agitation, and run af skimmer 24/7.


Andrew Butler said:


> can you fit an additonal inline solenoid to one? Unsure how this would effect the other if they were both regulated individually?


I could add another solonoid on one hose I think. If the tube and attachments can hold 20 psi pressure.

I've done a little tuning and monitoring. My PH today was 7.5, and reaching 6.8 is done in 2 hrs. Continues to drop to 6.6 but, inhabitants doesn't seem to care, however I only have shrimps and some ottos in there.
I might back of a bit on the CO2 at 6.7-6.8 and then start it 3 hours before lights on.


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## jaypeecee (11 Apr 2020)

kilnakorr said:


> Continues to drop to 6.6 but, inhabitants doesn't seem to care, however I only have shrimps and some ottos in there.





JPC


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## Andrew Butler (15 Apr 2020)

kilnakorr said:


> I could add another solonoid on one hose I think. If the tube and attachments can hold 20 psi pressure


It doesn't look like there's a distributor in Denmark but a company called 'DMfit' make a variety of different fittings which should fit your requirements on the pipe fittings front and I've a stash of varying fittings here which I might be able to help you with but suggest getting in touch directly if you wish to explore this further and I'll see if I can help you out.
The solenoid I'm sure there will be one that suits your requirements but not something I've looked into properly before; I imagine someone has, somewhere though.


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## kilnakorr (16 Apr 2020)

I little more tweaking and new ideas later and my CO2 is know 6.8 and stable.
I actually added a second powerhead for flow as I had a 'dead spot' in the tank. The types I'm using can output from 400 to 4000 liter per hour. They also have a light sensor that enables them to turn to lowest setting (400 lpr) when dark.
So the extra powerhead is angled to make more surface agitation when lights come on and increases offgasing of CO2. This seems to create the stable levels I'm looking for.


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## dw1305 (16 Apr 2020)

Hi all, 





foxfish said:


> Or in other words (maybe?) if you had a bucket of pure RO water and added a single element then that element might be detected quite accurately by the test kit but if you then added several other chemicals then the test results might well be effected and become inaccurate?


That is pretty much it.

If you want an analogy it is like a colour photocopier, you can photocopy primary colours and get really good replication, but if you <"photocopy a bank note">* it can't replicate the different tones of brown, mauve, pale green etc.

cheers Darrel

*(allegedly)


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