I have my horsies in a 29 gallon biocube! The lid is off so I have my own LEDs on there and the black strip along the top gone, so it has a "rimless" look. I think it's a good idea to ditch the cover; it will allow you to fit more in the back compartments, like a protein skimmer, light for the fuge, etc. Plus with the lid off, the temperature has been easy to maintain. When summer rolls around, it will also be easier to set up a fan in case the room temp goes up. It's been fine for my horsies so far, but yes, cover the intakes, whether on the tank or on any powerheads you have in there.