It wasn't exactly our set-up, least it shouldn't be. We got Bixby about 3 days ago, might have just not noticed the markings.
But for now since Yvonne said to keep the substrate dry, I will let it dry out a bit. Right now we have a wet, humid end a more dry end and the dryest end where he tends to sleep. Temp is about 80 and humidity is 80 as well. Now that we have our daytime UVA/B light the basking area is at 95. The basking area is also in the wet part of the tank (not wet but very moist).
We use cypress mulch substrate. Believe it was called forest floor.