I bought an rhp that goes the whole length of my tank bc my temps in the winter can get bad and I run air conditioning in my house during spring and summer. How I get a gradient is by also using a heat mat for the hot side. It also allows me to run the heat mat 92 to get a hot spot of 89 instead of having to run it at 95 to get 88. Which if you do what I'm doing you will need a herpstat 2
Is heating tape any good? I dont exactly have the money for a rhp (plus BP is gonna be in my room which has ac). Also, is a uth any better then heat tape?