Your 20 gal long, do you keep your heat lamp in the middle? I was told I should keep mine on one side of the tank, and I prefer the right side for the hot spot. I don't have lamp holders yet, so they're now sitting ontop of the tank, but I will be getting some. My original idea was to get for lamps and 4 holders to have a certain degree on the hot side, and a certain degree on the cooler side. Is that okay? My house gets very cold now that winter has arrived and insulation is rather bad.
Great idea with the top by the way, I never would of thought of it myself and I know now what I'm going to be doing here in the next week or so.