what watt for heat tape

what size or watt should i use to heat my 41QT rack i was going to use 2 strips on each shelf to heat one tub so 1 tub with 2 strips of 3 inc heat tape for 1 tub and use the left over stuff to heat my baby rack i am building with the shoe box tubs. but what watt should i use 10 watt or 6 watt ?

I am not much help here. My 41 has a 12" piece of 11" on each shelf, I just rather use 11" and get more surface area;)

i went with 4 inch 8 watt for my rack and on the bottom shelf i have a 41qt and i just put 2 pieces side by side. If ur rack has only 41s then i would go with the 6 inch or more. The wattage is not a big deal as long as u have the thermostat. Itll still keep it at a set temp. But if it gets really cold where ur keeping the snakes go with a higher wattage just to be safe.