Ahh got it, so you have a bit of a unique situation then. Cool set up btw, looks great!
Since you're heating a tub, I think in my case being directly on the pvc itself, instead of covering the entire bottom with heat tape I'll cover 2/3rds of it to allow the cool side to cool down a bit more. It should still allow a warm ground for digestion while still giving an opportunity for the cool side to cool a bit more with the RHP and tape.
Is there a specific heat tape you guys recommend or any to stay away from?
Also, side question with those of you that have an 18in high cage, do you prefer the 18 over the 12 and why? I did order the 12, but if you all feel the 18in height is much better for whatever reason, I'm sure I could call them tomorrow and pay the difference for the 18in. But perhaps with my cold room, I'm over complicating things, it's not actually necessary, and I should just stick with the 12in.