# DIY CO2 and night



## It's Me (Jan 14, 2008)

If plants create O2 during the day from CO2 and give off CO2 at night from O2 then what do you do with your DIY CO2 systems at night? I moved my hose and put in inside my HOB filter. Well after 10 min my plants were producing O2 like crazy. I took a video of one plant that had a constant stream of bubbles coming out of a cut in it. So it got me thinking, will I overdose my fish at night? Thanks for your help


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## Diana K (Dec 20, 2007)

What size tank and describe your DIY CO2 set up. 
Since there is usually no way to turn them off you might need to add an air bubbler that comes on only at night.


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## It's Me (Jan 14, 2008)

It is only a 20 gal. I know that you have to be careful with a tank this size so I put in 1/8 teaspoon of yeast. This produces one drop every three seconds. It goes through my HOB filter and into the tank. So far I have not had any problems with fish. I watch them closely and they are doing fine. I don't have an airstone in the tank but that might not be a bad idea. I did have three shrimp die close together and could not figgure out the reason. My levels are all stable. 

N02=0
N03=0
Amonia=0
KH=120
GH=75
PH=7.0
Water Temp=76°


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## hoppycalif (Apr 7, 2005)

The way to tell how much CO2 is in the water is to use a drop checker, with known KH distilled or deionized water in it. Bubble counting doesn't tell you much. DIY CO2 rarely produces enough CO2 to get too much in the water.

Why are you using CO2 when your nitrates are at zero? Plants can't grow without nitrates in the water unless you are doing an el natural type tank with the substrate providing all of the nutrients.

The best way I know of to "shut off" DIY CO2 at night is to use one of Tom Barr's internal venturi type reactors, which are cheap to make. This works because it efficiently mixes the CO2 into the water with the power on, but very poorly mixes it with the power off, so it is effectively shut off at night. Here is one thread about making one: http://www.aquaticplantcentral.com/.../31026-barr-internal-venturi-co2-reactor.html


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