Hey, so my tub's dimensions are 40 x 20 x 6.125 inches. My heat mat is 10 x 20.75 inches. How much of the bottom do you want it to cover?

The UTH covers about 1/3 of the tub if I lay it vertically. If horizontally it covers about 1/2 but it doesn't touch the sides of the tub, only the middle.

I'm opting for vertically as 1/3 of the bottom seems right from what I've seen to create a proper gradient. What do you guys think?