What type of rack are you using? I dont think you need a blanket for the rack, i would use one of the unoccupied tubs in the middle of the rack for the helix probe, set the thermostat to 92-93, you should get the gradient you are looking for 91-90 to 80, unless the room is really cold. If you have the probe set in a tub, you should see less temp fluctuation. Good luck.