If you do a false bottom then the UTH cannot be used on the bottom. The water on the bottom reacting with the heat from the UTH could cause the glass to crack. You would need to make sure it's on the side, away from the water. What I was talking about is a small aquarium heater to put in the water in the false bottom. UTHs tend to not be very reliable with keeping temps so maybe another heat source would be better? Then again if you already some laying around, why not give it a try?