They are in stackable tubs, not sure of the american quartz size. 60 cm x 35 x20 approx, so sticking a heat tape on the side might not work.
Anyone had any luck using heat cable around the sides to bump ambeint temps.
My temps were very similar to yours when i had them in the other room by the heater. My ambient was around 82 f.
Last check i made with a temp gun was in there new environment 89 hot spots 80 cool spot with an ambeint of 68 in one tub and 72 in the other. (yes i know these are really low)