you can put a UTH under a sterilite, but you better have it on some kind of rheostat or thermostat cuz most will run up about 100* which is BAAAD. Rack thermostats will depend on species. You could have one thermostat controlling multiple cages if the heat requirements for each species are the same. I have my thermostat controlling the flexwatt for my BP and my two carpets, but they both like the 87-90* heat range.