Since your che is giving you proper hot temps and cool temps then there is no need for a uth. The only way I see you needing a uth would be if the cool side was less than 75 then you could use uth for hot side and che to keep your cool temps up or another regulated che on the cool side but if it keeps your cool side temps 75+ while keeping your hot side 88-90 then there is no need for the uth or any other heat device. IMO 92 would be the very max I would go, if at all possible I would keep it closer to 88-90 so there is more room for fluctuation in temps without harm to your snake.
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