How long for co2 to drop? - The Planted Tank Forum
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post #1 of 3 (permalink) Old 09-02-2015, 09:27 PM Thread Starter
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How long for co2 to drop?

Hey all!

Setup my first planted tank, after years of un-planted tanks and poor attempts. And I'm going 'all in' with a high tech tank setup this time around.

Anyway, I'm running pressurized co2 with a solenoid and a T5HO lighting setup on my 29g. I got the co2 dialed in so that the drop checker stayed a nice lime green. Shutting the lights and co2 off at night, in the AM, it was still lime green. So the next night, I left the lights on, but still cut the co2 (thinking the plants would suck up any remaining co2). And it was a darker green, but still not back to blue.

Will the drop checker not go back to blue? Or does it just take that much longer for the co2 to drop? I'm wanting to dial things in so I feel confident stocking with fish shortly. I'm using a basic glass drop-checker with a pre-mixed solution. I did go ahead and change it this morning with fresh solution, which was of course initially blue; and I came home this afternoon to a nice lime green color.

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post #2 of 3 (permalink) Old 09-03-2015, 04:47 AM
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A lot depends on the amount of surface disturbance driving off the gas as well as the amount of plants you have and whether all the other things they need are in place, (your micro and macro ferts, light etc.). The better your balance of light, co2, ferts etc. the faster they will consume the co2. If you do not have a good balance of all those things then the plants will not grow and therefore they will not use the co2 or the fertilizers that you do have. You can have everything they need except one fertilizer and it will be almost like there were none of the things they need.

I don't use a drop checker. instead, I take a sample of tank water in a jar and run an airstone in the jar for half an hour or so and measure the PH. Then I measure the PH of the tank itself. The water in the jar has been de-gassed by the airstone so it has no co2 other than what is always present in air. My water reads about 8.2 My tank water reads about 7.0 which should put me very close to 30 ppm of co2.

PH pens are cheap now, (I got mine with a TDS pen for less than $20.00), and they are very accurate so it makes it easy.

Also, some drop checkers change pretty quick like in an hour or 2 but others may take several hours to change. They always tell you what the co2 was, not what it is.
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post #3 of 3 (permalink) Old 09-03-2015, 05:03 AM Thread Starter
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Thanks! That's helpful!

I am not dosing ferts yet; those come in tomorrow, actually. So that might explain slow co2 drop. I just wasn't sure what to expect.
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