I usually use a little piece of reflectix insulation (bubble wrap insulation) placed over the probe. With the probe uncovered it will lose heat into the surrounding air fairly quickly so will cycle the thermostat back on, at the same time the tubs will have retained some of the heat from the heat tape and thus when the heat tape comes back on it will already be warmer than the location the probe is at, so will eventually get warmer than the probe set temp.