What cheap thermostat do you recommend?

[rabernet]

Ummm im confused. Am i reading this right? Put the probe directlly in the heat tape? Heat tape warms up to 115 degrees plus when it cycles on so it would never keep tubs at temps and constantly cutting on and off

Not if you use a proportional thermostat, which controls the amount of power going to the tape to control the temp and doesn't turn off/on.

Besides, when you tape directly to the flexwatt, you're going to set your thermostat higher to account for the density of the tub and substrate to get to the desired temp inside the enclosure.

Whether you choose to measure the heat inside the temp by taping the probe inside the enclosure (not recommended under any circumstance) or you tape it directly to the heat tape, the amount of output will be the same to achieve the same temp on top of the substrate.

IE, if you were to temp gun the tape to see how hot it really is if you're a "thermostat probe inside the tub" person, you'll see it's the same temperature as it would be if you were a "thermostat on top of the flexwatt" person. Either way, the actual heat tape itself has to reach a certain set temp to effectively heat inside the enclosure.