[Carol]

I was evaporating at the rate of 1 gallon a day & found I could cut this in half by putting a lid on the tank & sump. Any reason I should'nt do this?

[scubadude]

Yes there is reasons why you shouldnt do that....Oxygen exchange will be cut down drastically....also this will heat the tank up and cause problems.....the most effecient way to cool a tank is evaporative cooling so IMO I would not put lids ontop of your sump/tank...just asking for trouble

[kevinpo]

You don't list your lighting in your profile but with a 55gal and 2 damsels you shouldn't have any problems with oxygen if your tank top is mostly open and the surface water is moving. Heat could be a problem but if you don't have one now then just keep an eye on the temp. As scubadude points out evaporation uses the least amount of energy if you are trying to cool your tank (he lives in Florida). In Missoula you have cold dry air like here (Spokane) and overheating is much less of a problem. My 90 gal evaporates about 1/2 gal a day and the sump is covered but it has no glass over the top only a hood with 1 - 175W MH bulb.

HTH,
Kevin

[eses]

I've found covering the sump, but leaving the tank open reduces evaporation alot in my system; but doesn't cause a temperature raise or low gas exchange. You want some air near your water, if you can just cover any areas where the water may be bubbling or splashing (where it feeds into the sump perhapes) I've found that is where most of the evaporation comes from.

[Northman_with_reef]

I covered 4/5 of my tank and i ended up with cyanoe and bryopsis......
And I only had 3 small fishes in it!!!!!!
(covers=BAD)

Thomas