For space-conserving purposes, I've been toying with the idea of putting my 20 gallon tank above the radiator in my room. It would be on a shelf (capable of holding the weight) about 4 inches above the actual radiator, on a thick slab of wood. Could I put something under the wood (between the wood and the radiator) to help deflect the heat away from the tank? Granted, we keep out house about 68F-70F during the winter, and I have fish that need warm water anyways, so maybe the heaters just wouldn't have to be running full power all day to maintain temperature. But with the tank directly above I just worry the temps would get too high.