Adjusting Needle Valve For Stable Co2

Harris Tiu

Member
Mar 16, 2019
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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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Joao

New Member
Dec 26, 2017
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Ideally you should dispense CO2 2 hours before light on and only turn it off 1 hour before lights out and aim for 30 / 40ppm. I always keep medium surface movement without breaking water. All you´ll need to know will be here:
 

Tim Harrison

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Crikey there is a danger of overcomplicating, just get a drop checker and read CO2 Measurement Using a Drop Checker
In a nutshell the start time determines the injection rate, which in turn determines the CO2 concentration throughout the photoperiod.

For example, my CO2 comes on 3 hrs before lights on, this gives me optimal CO2 conc at lights on and an injection rate that keeps it that way throughout the photoperiod.
If my gas came on 2 hrs before lights on I'd have to increase the injection rate to get optimal CO2 conc at lights on and then at some point during the photoperiod there would be too much CO2 and I'd end up gassing my critters.
 
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shoggoth43

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If your gas exchange is decent you wouldn’t have to worry about gassing your fish. Around 4:30 he explains the potential dip and instability and the resulting risk of gassing your fish if you do not have excellent gas exchange. That instability can cause you some issues.
 
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Tim Harrison

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You still need to be very careful. Although good O2 saturation can exist side by sdie with optimal CO2 conc it is still very possible to gas your critters.

I have a surface skimmer that keeps the surface clear of bio-film, and lily pipes creating a gentle ripple so I have pretty good gas exchange, I also have a Twinstar running, and the tank is densely planted. The water becomes super-saturated with O2 fairly early on in the photoperiod; that's when my plants start to pearl. But my critters will still be gassed if the CO2 is turned up too high.

It's been a while since I saw Dennis' video but I think what he means is that good gas exchange helps achieve the desired CO2 conc quickly and then to maintain it throughout the photoperiod, without noticeable fluctuations.

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