Here's how the tank usually looks



Here's what's in it



Left side is the warm side with a UTH - temps around 91
Right side is cool side (and the side she almost always stays in) - i try to keep the temp around 82, but they vary a lot.

I live in Lubbock, TX where the temps have a pretty wide range, and can change pretty quickly.
I only have air units in my apartment, so I can't really control the temps inside. I try to keep it on the warm side, but the window units seem to have a mind of their own.

Often times I'll check the temps before bed and they will be 82, check again in the mornings and they are 78.
Or if i go to work and they are 82, come home and its up to 87.
(these temps are from cool side, warm side is pretty consistent)




What kind of options do I have?
Is there a UTH that has multiple heat settings? The only ones I've seen in stores around here just have the default one, and that would be too hot.