I've been battling with my set-up (two bp tubs) for ages to finally get steady temps. The accurites are reading 90-93 on the hot side, and 75-80 on the cool side. That's after what seems like a month of moving stuff, tweaking stuff, etc. Well, I got a temp gun (finally) the other day, so I thought I'd try it out. I open the tubs and take a reading. It's telling me that the tubs are 70-71 on the cool side, and 80 on the hot side... wtf? That's a HUGE temp difference, and dangerously low if it's reading properly. All batteries are new. What gives?

I'm heating with flexwatt and a Ranco therm. all from Reptile basics. They aren't old equipment by any means.