Heat gradient

How do you keep a heat gradient inside a tank?

I'm having a few issues because inside my ball-pythons hide it gets above 90f if I have the heat lamp on that side (hot side) but then without it on (cause the thermostat turns it off) the air temp on the cold side falls below 76f, If i put the heat lamp on the "cold side" the air rises to 89f but keeps the air of the "hot side" (with the hide) at 81f, and the hide at 89f

What I need to know is how can I have a hot & cold side without making the hide too hot?

What temp is the hide supposed to be?

The pic below is of the current setup! Its kinda crappy but works for now until you guys help me out haha :D

http://img195.imageshack.us/img195/3447/tank100.jpg

I would use a lower wattage bulb (and blue it is farther off visual light for royals)

Inside the hide should be 90ºF warm 80ºF cool with air temps between 78-85ºF

If you insulate the side of the atnk it will hold more ambient heat as well. A rheostst on the bulb may also be a big help as you can tune the power of it.

Would black be ok?

The current red light that is in there is 75W go down to 50?

Would a black one be better than blue/red?

What can I insulate the sides of the tank with?

Should I only insulate the hot side?

Thanks!

Foam core or foam insulation, 50w might do it hard to say a dimmer would be easier. No black light is UV they don't see it but too much UVb/c is bad for both you and them. Yes black background would be fine anything really.

Do you attach the foam core on the outside?

How thick should it be?

Any pics?

Total noob! thanks!

Yes on the outside. 1/4 is ok 1/2 better. 1/2 inch foam core is hard to get but blue foam insulation is easy in 1/2 1+ any hardware place will have it.