i started out with a 20 g tank. after messing around with heat lights ( waste of time ), i bought 2 exo terra heat pads. One was the rain forest pad, that gave me temps in the low 80's. i think its the medium one but i do know it was about 8" x 8". then for the hot side i bought a desert exo terra which was a higher wattage and gave me temps in the low 90's. If u find the heat is too high, just use a thermostat or too get u going, u can start off with a dimmer. good luck.