Ok here is the verdict with the infrared temperature gun.
I made one tub have a single strip of 3" flexwatt tape. The other tub has two strips of 3" flexwatt tape.

Heat tape measures 95 degrees

Single strip tub
Hot side = 85 degrees
Cool side = 76 degrees

Double strip tub
Hot side = 88 degrees
Cool side = 78 degrees


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