i've been using heat pads. however, my roommate who is home during the day left town suddenly so i dont have anyone to monitor the temperatures during the day. i didnt know i could use one. but i may be calling it the wrong name. i have my BPs in one room, but they are in seperate tubs and tanks. I have one in a tub because she's just more comfortable there, i just moved another to a tub to get her to eat, the other 3 are in tanks. i dont have them in racks.