[ggsteve]

I have a DIY yeast CO2 reactor on my planted 150. Until it begins producing CO2 I just hang the hose in the tank until it starts bubbling. It occurs to me that this CO2 rises to the surface and then, since it is heavier than air, it must sit on the surface of the water below the level of the tank rim. Is this a) effectively adding CO2 to my water, b) forming a carpet of death that suffocates my fish, or c) pretty much nothing at all?

 

[Sugardaddy1979]

I doubt you are able to hold a concentration of CO2 so dense that O2 isn't diffused via surface agitation. What kind of tank cover do you have?

 

[kevmo911]

C).

 

[Bettatail]

I have a DIY yeast CO2 reactor on my planted 150. Until it begins producing CO2 I just hang the hose in the tank until it starts bubbling. It occurs to me that this CO2 rises to the surface and then, since it is heavier than air, it must sit on the surface of the water below the level of the tank rim. Is this a) effectively adding CO2 to my water, b) forming a carpet of death that suffocates my fish, or c) pretty much nothing at all?

it is the concentration and plus low level of O2, co2 will be poison.
check the link in my signature.

 

[ggsteve]

I doubt you are able to hold a concentration of CO2 so dense that O2 isn't diffused via surface agitation. What kind of tank cover do you have?

I have a fairly tight fitting glass cover, except in back where the heater cords and filter plumbing enters and leaves. The T5 light hoods sit on the glass and then a well-ventilated oak canopy (the old "Classic Oak" series by All Glass) covers the mess.

 

[Slingo]

I have a tight fitting glass top and drilled a small hole for a co2 line. There is very little to no air exchange much like yours. I have no problems with co2 deaths or poisoning with my shrimp or fish.