CO2 tuning - need help

kilnakorr

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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?
 

Zeus.

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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 ;)
 

kilnakorr

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Thanks @Zeus.

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

...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.
 

Zeus.

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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 :thumbdown: so back to step one :banghead:

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 :angelic:

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.
 

kilnakorr

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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.
 

kilnakorr

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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?
 

Zeus.

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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?
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 :eek: :lol:)

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"
 

kilnakorr

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

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

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

kilnakorr

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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.
 

Zeus.

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put your ppm into my 'Water Report Wizard'
upload_2020-3-29_12-39-19.png


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

upload_2020-3-29_12-41-55.png


(its states my tank size but that irrelevant ;))
 

kilnakorr

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

kilnakorr

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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).

20200329-150518.jpg

20200329-150537.jpg
 

Zeus.

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

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 ;)
 

kilnakorr

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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.

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;)
 

milesm

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HI
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?
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.
 

Andrew Butler

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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?
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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