Temperature Gradient

[Didymus20X6]

I noticed in your pics in the other thread that you have a swimming pool for your snaky. Trust me, if he gets too warm, he'll take advantage of it. You could put a brick in the middle of the pool, and if he wants to just have a nice cool place to rest, that would be perfect.

[Sonya610]

You could also use cold packs (the plastic freezable packs they use to keep items cold during shipping, they are reusable just keep freezing them). Since they are flat (if you freeze them that way) they could be laid under a tile or a water dish and they would probably last all day. You could even put a few under the tank on the "cool side", hopefully you do have a thermometer to monitor temps.

It is easier than ice, lasts longer and doesn't melt into a soggy mess. If you have a piece of foam insulation you could cut it to the size of the tank, put the packs under the glass and the insulation below, that would probably last for quite some time.

[ConcinusMan]

Even the gel packs will "sweat" (condensation) if your humidity is correct so I suggest putting them into the water or at least set it in dish to catch the water that comes off of them.