Not only do you not want the glass on for heat issues, it will also cause issues with the gas exchange, which can affect things like your pH. I have egg-crate on the top of all of my tanks and will only ever use this stuff to keep in the jumpers.
Originally Posted by SkimmerFly
I'm kind of in the same predicament. I switched to MH. Should I take the glass tops off? Sorry if I hijacked this.
You should definitely take the glass off if you are running MH. The heat buildup will be insane!