Adjusting Needle Valve for Stable CO2

FishWorks

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Guys,

I am currently in the aftermath of my planted 75g crashing.
Red plants died, Monte Carlo fading yellow.

I dispensed the CO2 Gas via powerhead as my tank is 4 feet long.
I believe I had running medium light.
Also, I had a Canister Filter with a spray bar creating some agitation a little below surface water.

Everyday, My target was 30ppm CO2 at about 1 hour before Lights OFF.

I've done some research and found out that Target CO2 levels should come at Lights ON.

IF my CO2 injection starts 1 hour before Lights ON and the rate of injection is about 5 BPS. Then finding my CO2 concentration is about 30ppm at Lights ON...


My question is:
After the first few hours during Lights ON, the CO2 ppm levels should plateau right?
I mean that CO2 concentration will eventually level out and stay there?

I suppose I could test with my terrible API test kits but would prefer some advice from experiences aquascapers.

Kindly please share tips about target CO2 and stability of CO2.


Thanks,
-Harry
 
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ian_m

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If you have your injection rate set correctly, kind of matching the losses then that is the idea.

Straight off I will say you will definitely NOT have 30ppm at lights on after only one hour. Look at the monstrous plumbing and injection rate and controller Zeus uses to get 30ppm in his tank in an hour (see featured journals).

If you did have injection rate to get 30ppm in an hour, it will go seriously higher with that rate following lights on.

How are you determining you have 30ppm all over your tank.
 

FishWorks

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Ian,

I updated my original post to better describe what has happened.
My old system was a 75 gallon and it has crashed :(. I am new to planted tanks. I just jumped in the hobby as my cousin gave me his old 75 gallon.

I use API PH and KH test kit and cross reference with the CO2 table (i have read this is inaccurate). I actually just ordered a Hanna Instruments PH and KH meter though it hasnt arrived. I plan to rescape in a 100 gallon, 6 feet long x1.5 x1.5 then use these better testing equipment along with the knowledge I get from this forum on how to start better.

So what if I started the CO2 2 hours before Lights ON and reached 30ppm 2 hours after Lights ON? would that be something i can maintain throughout the photoperiod?
I also thought about 3 CO2 systems running together. Each with their own bottle, regulator, solenoid, bubble check, etc.
its going to be 3 CO2 systems being dispensed by their own powerhead.
 

ian_m

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No you want 30ppm when the lights come on and the plants start requiring carbon as driven by the light. Generally plants will suffer, holes, mechanical damage and algae if sufficient CO2 is not present when lights are on.

3 injections of CO2 is preferable to one large injection in a large tank, again see how Zeus has managed decent CO2 levels in his monster tank with two injectors and reactors and gyre wavemakers.
 

FishWorks

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Ian,

So bearing in mind the loss of CO2 by surface agitation, I need to match this with the right rate of injection.
I could start the CO2, 2 hours before lights ON and have 30ppm at lights ON. Then hopefully maintain this concentration until lights OFF.

Basically, its a matter of properly tweaking the needle valve?

Thanks,
-Harry
 

FishWorks

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I suppose I could have some cheese and wine with this? :clap:
I did understand the calculus though I am only as far as integrals at the university.

How long would you recommend plants be at this 30ppm concentration? 6 hours maybe?
My last tank, started at 6 hours photoperiod and had hair algae and GSA and some bushy staghorn. When i got up to 8 hours, only the staghorn remained which I would manually pluck. Been contemplating doing 10 hours next attempt but thought about saving the electricity and CO2.

Also, I've read that the standard 30ppm for hi-tech tanks is now 40ppm since year 2008. So a medium light would be kept at 30ppm?
 
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FishWorks

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Zeus,

Could I ask, If only 4 hours of medium light at 30ppm CO2 be enough?
If plants only need 4 good hours of photosynthesis, that is quite short.
I dont want to say unbelivable but, it just sounds too easy.

My current knowledge is that 6 hours of light at 30ppm CO2 is minimum for hi-light.
 
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Zeus.

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Well its not my quote but Clives aka 'Ceg4048' who is the Guru on here for everything CO2. His quote is for '4hrs or so' not 4hrs and it is light dependant

I will give you his full quote
if you are struggling with CO2 stability, or are having difficulty keeping high concentrations, then it's best to focus efforts on the first half of the photoperiod and not worry so much about the second half. If you are running very strong lighting then you are really pushing the plants and it's necessary to have the CO2 going. After 4 hours, if you turn the gas off, the water stays saturated for a couple of hours after the valve closes and the concentration trails off. So if you have an 8 hour photoperiod and you turn the gas on 2 hours before lights on, you can turn the gas off after 6 hours. So the gas is still running for 8 hours but it's on-off cycle is offset by the amount of time you turn it on prior to lights on.

There is no need to run the gas for 10 hours therefore.

Plants don't really run their photosynthetic machinery for the full day anyway. Under normal conditions, after 4 hours or so they start to shut down, so that's why CO2 isn't really needed for the full photoperiod.

Long photoperiods benefit algae more than they do plants, especially if it is high intensity.
The long photoperiod is more or less for our enjoyment.

How you work out what best suits your setup you will work out I'm sure, But Clive quote is for 'HIGH' light and after 4hrs or so, with meduim light they my not be done with the CO2 also ! just to throw a spanner in the works
 

FishWorks

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Well its not my quote but Clives aka 'Ceg4048' who is the Guru on here for everything CO2. His quote is for '4hrs or so' not 4hrs and it is light dependant

I will give you his full quote


How you work out what best suits your setup you will work out I'm sure, But Clive quote is for 'HIGH' light and after 4hrs or so, with meduim light they my not be done with the CO2 also ! just to throw a spanner in the works

I suppose I could just observe the plants throughout the photoperiod then shutdown lights and CO2 injection once I see the plants closing up.
But I've read about luxury uptake by plants. not sure if it was from Clive I read that...
 

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