well i run the heat rope back and forth once per level and take it frm bottom to top(remember to to not use about 2 foot from the plug it should be mark as it doesnt get hot) when all laid out i pick the center row and put the thermo probe there now keep the temps at about 94 there and it should keep all the tubs between 88 and 92 (assuming your keeping balls)
you can also go to there site or zoomeds site to get instructions