Thats a 20gal tank so that 60 watt CHE isnt going to cook the tank at all so dont worry. Unless your house/room is over 72° let it rip on the cool side.. I put mine on the screen of my quarantine tank without the Dimmer because if you need to you just raise the CHE higher to decrease the heat. As long as you cover a good part of that tank with Tin Foil and a hand towel you should get 76-80 on the cool side. (Keep the towel a inch away from the CHE)
Looks like your getting things dialed in![]()