So I finally got my external filtration system up and running on my 15 gallon (canister, pump, CO2 reactor, UV sterilizer, heater) yes it is a bit overkill for 15 gallons but it is a display tank. I bought the 1/2" Hydor 200W model since it was the smaller, but 200W is too much for a 15 gallon I think. The problem is it cycles on and off literally every other minute. I can see how this would maintain a very accurate temperature but I would think it will shorten the life of the heater which is not cheap. I have already noticed jumps in my power bill from 25-50W aquarium heaters so I will be curious to see what this does. Is it worth running a standalone temperature monitor or is it just a waste of money? Will it run my heater more efficiently? Is there a way to somehow use a voltage regulator between a temperature monitor and my heater to throttle down the heater consumption? If this unit dies on me within 1-2 years I will replace it with a DIY in-line sleeve of some sort that accepts a heater of my choice.