Not sure what you did but in my 20x12x12 tank I had problems keeping temp steady with my 50w Che and the uth then I got a bigger fixture and covered the top with tin foil and 150w bulb and it was just makin it way to warm so I got 100w on dimmer using Eco earth and cypress mulch mixed and hot spot is uth at 92-93 with the Che centered keeping it at 79-83 degrees with a substraight temp of 85 and humidity is around 70% with fresh change on it