You don't need a thermostat or anything else just a UTH. The only temperature you need to worry about is on top of your bedding. A warm side hide about 85 and a cool side hide about 75 degrees. You can read what Don from SMR wrote on the same subject. Here it is (with his permission) :
No thermostats necessary . .
I haven't read each and every post on this thread, but am compelled to offer some observations, in response to the general tone of thread participants.
Ball pythons love to cook themselves (probably other species too), but not corns. I personally have never had a corn burrow down to the hot plate below and get burned. Of course, I can't say it hasn't happened to someone, but I have some statistics to offer.
I sell over 2,500 neonate corns annually and have done so for over eight years. Before that, I probably sold at least 1,000 per year for over five years, and so on. Let's just say, I'm certain I've sold well over 35,000 corns. 80+% of my customers are buying their first snake, so you can imagine how much time I spend with them, going over environmental requirements and answering newby Qs. I'm positive that over 98% of my customers are using UT (Under Tank) heat and I'm equally certain that 98% of those are NOT using thermostats. These stats come from speaking to customers that call to discuss heating, watering, cage furnishings, shedding, feeding, etc.. Out of those 35,000+ snakes sold, not one single person ever called to ask me how to treat a belly burn (or any other belly sore). In all the years I've been keeping snakes, not one corn of any size ever burned itself, while in my care.
Observations:
The stats speak for themselves, but only because of the efficiency of what I call the passive rheostat, (aspen substrate). If you put the UT heater under one end of the cage and have a one to three inch depth of aspen bedding (or similar bedding product), corn snakes will NOT burn themselves. One key to the success of this safety is remembering that corns like to hide. If you adjust the depth of the substrate to result in a temperature of 79-85F INSIDE the warm-side hide, your corn will spend 80+% of it's life in that hide. As long as there is another hide (also dark and seclusive) on the cool end of the cage, the two hides are where they'll spend most of the daytime hours of their lives. Only if the warm-side hide falls below 79 will they seek warmer digs, BUT I have never seen nor heard of one burning itself on the hot glass below. If they do burrow, they seldom go to the glass and often if they do go that deep, they can be found inches from the warmest part of the glass. No burns result.
Note: If using a thin floor covering in the cage such as newsprint or paper towels, thermostats and/or rheostats are recommended.
Now, having given you personal testimony about the many thousands of snakes I've had in my care, and that of many thousands of other customers and associates that do NOT use thermostats, it should be obvious that corns CAN thrive in captivity without temperature control devices. I didn't mention the people that have called me over the years, crying about failed thermostats. Each time you employ the services of an electronic device of any kind, it's not a matter of if there'll be a problem, but when the device will fail. Granted, such a failure will be brief, but it WILL happen. I will not argue that using a thermostat or rheostat may be more energy efficient and that it will help maintain a more constant thermal gradient in the cage that is more conducive to digestion, but I can assure you that in the absence of a temperature control device, not only will the warm-side be safe and efficient for digestion (as long as the room temperature does not exceed 85F), but totally safe for your snake. Of course, if your room temperature exceeds 85F, even a thermostat will not help you avoid potential hyperthermia.
Note: If you are one of those that thinks thermostats are crucial to the welfare of your snake, are you using two of them redundently? If you really think a thermostat is crucial, surely you understand the need for a back-up that will kick in if the primary device fails. Otherwise, if the thermostat fails in the OPEN position, you'd better have a deep substrate depth, sufficient to protect your snake from the falsely perceived threat of it getting belly burned.
Thermostats may have some benefits, but they are definitely not a prerequisite to corn snake husbandry. I have tens of thousands of customers that will attest to this fact. There are hundreds of different ways to safely and efficiently maintain corn snakes, but it doesn't mean that one of those ways is the only way. If thousands of my customers are safely keeping cornsnakes healthy and free of thermal-related afflictions, it is safe to say thermostats are NOT essential. In fact, in some cases, electronic failure could result in problems, but even a run-away thermostat should not stick in the OPEN position enough to affect your snake, unless you have no cool hide in which the snake can retreat. I'm not verbally spanking anyone for their advice in this thread. I don't do that, since I know the way they're keeping their corns is so successful, they want to share it with others. I just want to show that other ways work well also.
Regarding the temperature of the glass above the UT heater; you can monitor glass temperatures over 130F in some cases. In the absence of using a theromostat or rheostat, and with sufficient substrate depth, your snake can enjoy low 80sF inside the warm-side hide.
Note: If the hide is not sufficient dark inside, they may burrow into the substrate to block the light from their eyes, but that is nothing to worry about. They will NOT get close enough to the heat source to get burned.
Regarding OT lights vs UT heaters, it's a no-brainer to me. In the wild, air temperatures can play a role in corn snakes achieving comfort and nominal digestion, but in captivity, there is little benefit to using OT heat. Not only does 80+% of the heat from a round incandescent light bulb never reach the snake, but the air in the cage is usually unacceptably dry as a result of that type of heat. Since heated air rises, UT heating is not only more efficient and beneficial to energy conservation, but a more natural way for snakes to achieve nominal metabolism. The ground on which snakes spend most of their lives in the wild, holds temperatures. Even when the night air cools the area above the ground, the ground surface retains much of the heat of the day for several hours after dark. Some nights would be too cool for snakes to hunt, if not for the core body temperature they're able to maintain from contact with the ground. Hence, heating your snake from below is the most natural way to heat snakes in captivity. Did I mention, there are no flimsy filaments to fail in UT heaters? Light bulbs are notorious for needing replacement from all the movement they endure and 60 watts of electricity is much more than the 8-12w a UT heater requires. What if you went on vacation during the winter and the bulb filament failed? Do you use two lights redundently, in case of primary failure. It is extremely rare for UT heaters to fail.
In conclusion, I'd like everyone to remember that many people reading these forums are impressionable and some readers actually react to everything they see here. If you think your way of keeping corns is elemental to your success, that's something you should tell folks about, but it's wise to promote open-mindedness about alternatives. I've always maintained that if you can't afford the basic requirements to keep snakes healthy, do not get one. But having said that, the added expense of thermostats and rheostats is not necessarily crucial, and can sometimes mean the difference between affording and not affording a corn snake. If I thought temperature control devices were a prerequisite to safe corn snake keeping, I'd only sell snakes to people that use them. This is not the case.
Merry Christmas (or any other holiday you practice this time of year) from
Don Soderberg
South Mountain Reptiles
www.cornsnake.NET
