how to set up a tub enclosure

[Kaorte]

im just wondering on this because i am going to build a rack soon and i have only heard of using belly or back heat on the warm side. wouldnt it effect the gradient?

I'm not sure I get what you mean.

In a rack setup, people either use 3-4" belly heat down the back of each shelf, or back heat down the whole back of the rack using 11" heat tape.