People complain too much about hydrofarm stats. . . I'm sorry but I have used two in the past and one that I currently have on a QT area and it works just fine with a tub - let me explain something. . .

Just because the heating unit is heating up and then going off and heating up and going off, your glass and substrate act as a small conductor which will hold the heat at temperature much better than a 6 degree temperature. When my QT rack runs on a hydrofarm, the hydrofarm is set to 90, placed to the side of the flexwatt, then an IR Gun measures the internal temperatures untill they are stable at 92 on the hottest point. I then check when the hydrofarm drops off and it reads 91 with the IR gun, and then I wait till it maxes out - again 92. This is using an RBI 30.6qt 4 Stack with the hydrofarm using a quality IR gun to check the hottest points. There is NOT a huge sway. Maybe I lucked out and got good units that I could work with. I'm not sure if the probe reads entirely accurate, but it makes my tubs at optimum levels and holds true. If I was in a bind I would not hesitate honestly. But I do prefer my herpstats on dimmer mode . . .

Just wanted to give my word on the Hydrofarms.