Going to buy the wood at lowes tomorrow and wanted to ask should i go 35in ches across or 24inches accross..35inches holds 41qt and 24inches accross holds 32qt and 15qt tubs so what tub would i use for the medium tubs if i went with the 35inches accross.Two more question where should i put the heat on the back wall or on the top of the shelf.and what kind of heat should i use im afraid of the heat tape on the shelf because when u pull the tubs in and out wont the heat tape break or tear....need some advice im ready to build..thank you.