# question from a rookie..



## dinop (Jan 31, 2010)

So I've got a 90 gallon tank loaded with plants, lots of them with a Co2 regulator setup on a timer that shuts off at night
I have various small fish about 40 of them.

I noticed at night my fish are all hanging out on top of the tank. Should I be keeping the Co2 on at night as well?

Are the fish not receiving enough oxygen?

I had an air pump with air bubbles with broke recently and wasnt replaced - should I replace it? I also have 2 water pumps in the tank which flow the water.


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## KnaveTO (May 13, 2007)

If your fish are hanging out at the surface of the water at night, then you should think about injecting O2 via an airpimp with an airstone diffuser. Do not have the air pump going while your CO2 is going as you will just counteract the needed CO2 injection during the daylight hours.


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## dinop (Jan 31, 2010)

so I am pretty sure the Co2 is injected through a tube and into a membrane of some sort where the air is dispensed. I followed Darkblades FAQ and have set up properly. the question is should I keep the CO2 running constantly?


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## KnaveTO (May 13, 2007)

CO2 during the day... O2 at night


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