Glass tank cover cannot hinder gas exchange?

StoutLager · #1 03/19/2006, 11:05 AM

I was told that having a glass cover on tank will hinder the gas exchange (oxygen in CO2 out). Is this true? How could the skimmer which is beating the water to death with fresh air not overcome this by a long way?
(lets ignore the glass hindering the light in this thread).

drock59 · #2 03/19/2006, 11:16 AM

you just pointed out the two drawback to glass covers. Why dont u make a canopy/hood and not worry about it?

jent46bow · #3 03/19/2006, 11:16 AM

it is possible. salt water does not hold o2 very well, so there is no way that your skimmer can provide o2 for the entire tank (unless it is a nano). Surface movment is far more important though than having a glass top or open top.

With all that being said I have run a glass top for the last 9 years on tanks sized from 30gal to 120gal. And I have NEVER seen any problems with Ph. IMO if you have enough surface movment it is neglagble.

MCary · #4 03/19/2006, 11:19 AM

If you are running a skimmer then there is plenty of gas exchange.

Logically I would say that the gas exchange in the tank would of course depend on surface agitation, the level of the water below the cover, and how tight the cover is. An airtight cover would of course hinder gas exchange (provided no skimmer or sump). Which makes me think that water agitating through the sump would have gas exchange also.

Mike

jent46bow · #5 03/19/2006, 11:24 AM

I would just like to add more description about my glass cover....first the main tank has a glass over over both sides with .5in open in the middle and .5in open in the back of the tank. I also have the sump covered except for about a 3x5in area where the skimmer outputs. I have this all covered to reduce evaporation in this desert like atmoshphere I live in. And so far I have seen no ill effects.

MCary · #6 03/19/2006, 03:10 PM

I ran a glass cover on my 80 gallon. I wanted to cut down on humidity (and did). I did not have gasping fish or lowered pH levels from increased CO2 levels. All inhabitants did fine as well as I could tell. I didn't like the glass getting hot from the MH and having to clean the glass often. But the gas exchange thing didn't seem to be an issue.