I am pretty sure that using an on/off thermostat would be no different than unpluggin the heat pad and then plugging it back in. There should be no way the thermostat could increase the output of the pad. As far as increasing air temp if you close off most of the tank lid with something to prevent air flow. That would increase air temp, by trapping the heat from the pad from escaping the tank (the same as if you leave the door open on the fridge, all the cold air escapes)