# For CO2, how long does it take before Drop checker changes color?



## pwu_1 (Oct 28, 2013)

For those of you that have your CO2 set on a timer, I'm just curious about how long it takes from your CO2 starting until you see the Drop checker change color from Blue/dark dark green to a light green/yellow color?

I'm diffusing CO2 through my HOB filter so I think I must be wasting a lot of CO2 due to surface agitation and gas escaping out the top of the HOB. I have my timer set so the CO2 comes on about 1.5 hours before the lights but my drop checker usually doesn't start to change color for at least 2 or 3 hours and it eventually turns a light green/yellow color usually about an hour or two before the CO2 is turned off again for the night.
My plants do start to pearl a little bit maybe 3-4 hours after the lights come on but its just a bubble here and there. Just curious if I should try increasing my CO2 levels even though I'm having to run a pretty high bubble rate already


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## Hoppy (Dec 24, 2005)

It takes 2-3 hours for a typical drop checker to read close to the correct color. Your HOB filter is probably greatly slowing down the build up of CO2 in the tank water, so the slow response you have is partly due to the drop checker and partly just the slow buildup in the tank. Increasing the bubble rate should help a lot.


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## 1987 (Jan 27, 2007)

Hoppy said:


> It takes 2-3 hours for a typical drop checker to read close to the correct color. Your HOB filter is probably greatly slowing down the build up of CO2 in the tank water, so the slow response you have is partly due to the drop checker and partly just the slow buildup in the tank. Increasing the bubble rate should help a lot.


100%

Usually takes about two hours for one of my tanks that I had sponge filters in. The HOB creates aeration of the surface which makes the CO2 escape quickly.


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