Sorry for the second question. I'm having a hard time keeping up humidity in my 20 gallon tank. I'm having to wet towels twice a day because my house is getting so cold and I'm having to use heat lamps on BOTH ends to keep ambients on hot and cold side up to par. If I put a piece of plexiglass on top and drilled holes, would it be be enough ventiliation or would I need to leave gaps at both end of the tank?