The 40 above with the uth keeps the hotspot at 90. I'm using reptile prime which is a coco husk substrate. Eco earth is a coco substrate as well but is dustier and tends to get muddy with too much moisture.
Temp probe one from a thermostat or thermometer? Two different things?
therostat probe goes between the glass and uth.
Thermometer probe usually goes someplace on the Hotside, cool side, and middle or all three. And never use tape inside the enclosure. A hot glue gun works better.
and my accurite thermometer/hygrometer does not have a probe. It sits in the front middle of my tank.