use a thermostatically controlled, water-safe heating cable in the substrate Do you have any specific ideas about how this would be safe to use in a moist environment??? Any brand names?? I have a lot of concerns about this heat issue since our very old log house is quite cold in the winter but am willing to invest in SAFE ways to heat my tanks... And since my barn burned to the ground several years ago using an "in stocktank" water heater...am sorta leary of some of them...and I've heard that the heaters can crack the glass...help...