glass top limiting CO2 exchange at surface?

[TammyLiz]

I am making a diy canopy and was planning on putting a glass top under it to reduce evaporation and condensation within the canopy. Now I hear from you guys at this forum that gas exchange at the surface in a non CO2 injected tank is a good thing and I think you have a point. So, I am wondering if my glass cover is going to limit gas exchange enough to keep CO2 levels in the tank below the levels of the air in the room if it is moderately heavily planted. I will be running a penguin biowheel 350b on it, which has a plastic cover over the biowheel unlike the older model. If you think the glass is a bad idea, what should I do about condensation on the lights? They will be sitting probably 4 or 5 inches above the surface. :?

 

[Lonewolfblue]

Do the glass tops have any way of having openings towards the back, such as where you would put hoses through or a HOB? If you have some openings in the back, that should give some flow into the tank and keep much of the condensation off the lights.

 

[Purrbox]

I would expect that your filter is going to provide the majority of the gas exchange in the tank since that is where the most water agitation will be. I think a better reason for deciding for or against a glass top is the safety of your fish. If you have fish that are prone to jumping or other critters that like to escape (read shrimp and/or snails), cover it. If not, then you can leave it uncovered for the possibility of greater gas exchange and better light penetration into the tank.

 

[malkore]

A glass top isn't going to affect CO2 levels in a non-injected tank. Even if it did, it wouldn't matter, as a non-injected tank shouldn't have strong lighting, so CO2 wouldn't be a factor.

 

[sherry]

I will say one thing about a glass top tank.. I wonder if filling my tank too high lead to some of those fish deaths.. since it was the hillstreams that went completely...

With my tank, I am making sure I am at least 1/4 inch from the tippy top from now on.. to aid in o2 exchange... I may be doing this for no good reason.. but honestly I can't think of any other good reason for the die off.. since it happened over night.. when plants were competing for o2, I think gas exchange would be a pretty important factor.

also.. Malk, I had high light 3 watts per... without injected co2 until yesterday.. just excel and almost everything grew pretty well.