hello guys,
I wasn't sure where to put this, so please move if needed.
As many of you know, I am preparing for a new boa. I'm putting him in a tub and am using this tub, the 110 qt. steralite. This tub's measurements are 34 5/8 x 18 3/4 x 12. I am planning on using a UTH for the hotspot and heat lamp (outside tub on cool end) for ambient temps.

My problem is this... I have this ultratherm heat mat , which should be perfect at 11' x 17" to heat 1/3 of the tub bottom.. The only issue is, the heat mat is slightly larger than that and the tub bottom is slightly concave.

Last night I got the tub setup. I attached the UTH to the surface the tub would be on, setup the probe and thermostat, etc. With the UTH attached to the table, the bottom of the tub did not come in contact with the UTH except on the edges, the center part of the tub was at least 1/2 - 3/4" above the UTH and it did not seem to heat very efficiently at all (I had it set initially to 91f and my thermometer probe was reading 80 in the tub over the UTH). After trying it at a higher setting (95) and still not getting temp readings in the 90's, I decided to attach the UTH to the tub bottom instead (the concave part).. The only issue with this arrangement is that the mat would need to be slightly bent / curved to match the concave curve in the tub, because it is too large to be seated solely where the tub is higher. With that setup, I got better readings, but very spotty (was using my temp gun).. Some areas of the tub over the mat read 93, 2 inches away, read 88, 83,etc.

I'm not sure if bending the UTH like in the current setup would cause a short down the road or is causing the spotty temp readings, but I'm also not sure I want to crank up the UTH to, like 99, if attached to the table in an attempt to heat the tub above it.. Neither of these seem like ideal situations to me.

I'm considering ordering a smaller UTH that would fit within the raised area of the tub and adhering it there, but again, I'd hate to not use the UTH I already ordered for this project just due to it being too big, and this would push back my setup date and mean that I'd have to wait longer to get my snake shipped.

If you guys have any input I'd greatly appreciate it.. I did not anticipate that this project would be so difficult.

Thanks!
Artgecko