Heat loss problem

I have my uth and thermostat all set up. The only problem is that i'm losing a substantial amount of heat from where the probe is to the top of the substrate. I'm talkin ten to fifteen degree difference. Could this be because of my substrate choice(cypress)? Is their another substrate that does a better job with heat?

How thick are you laying on the substrate. I use aspen and only about 1/2 inch and have no heat issues. Just a thought, you may not need to switch, maybe just use less?

Yes, I think your substrate layer is too thick. Inside my warm hides I have almost no substrate just a sheet of newspaper since my balls keep pushing the aspen away. Everywhere else its half inch to an inch.

I use cypress and had the same problem. I just reduced the thickness and it's fine now. Watch your RH if you got it from a nursery, it can get up there. I switched to a mix Care Fresh Basic and cypress. But then again I have only had it setup for two days, so take it with a grain of salt

How long has the heat been on with that substrate? Sometimes the loss isn't loss it is that the substrate is damp and takes a long time to heat up. Just offering a possibility.