American Marine Pinpoint Dual-Stage Temperature Controller + Probe

This temperature controller is phenomenal! I've been using it for roughly 8 months and it keeps your tanks water within 1 degree Fahrenheit.You can run up to 700 watts of heaters and a 1/2hp chiller simultaneously. I don't use the chiller side so I cap it off in the winter or plug a fan into it in the summer. But I really don't need it with the houses air conditioning.I use a 3-way split extension cord made by Webber with locking clasps because it's weather resistant, and plug in 3 - 200watt heaters for my 180 gallon saltwater tank.The way it works is whatever temperature you want, and you can set how much variance in temperature there is, the controller will keep it in a range of half a degree above AND below the set temp. So I wanted my temp set to 77 degrees with as little variation as possible. In this case you set the controller to 77.5 degrees because it ranges a half a degree in either direction. So it will kick on the and when it gets to 78 degrees it'll shut off the heaters. Once the probe in the tank gets to 77 degrees it kicks back on until it hits 78 again and then shut off until it's back to 77.You really can't get any better temperature controller. Heaters will always eventually fail, whether they get stuck on, and cook your tank, or don't come on at all, and freeze your tank. This controller eliminates that worry. It can't overheat because it shuts the heaters off and if 1 heater dies I still have 2 more to keep the tank running smoothly.Yes, this is a VERY expensive temperature controller, but I wanted a USA product that isn't as likely to fail as the heaters. There are plenty of Chinese temperature controllers on the market and they all have issues. It can even be calibrated, but is reliably set at the factory. I keep another digital thermometer in the sump to keep the controller honest.I also don't have a need for a whole tank control system that costs $800. But you need something to monitor your heaters. Because it's not IF they will fail, but when. And you should always split up the amount of heaters you have. If you need 600 watts of heaters, use 3 - 200watt heaters instead of 2 - 300watt heaters. You want to be able to keep your tank stable if one should fail, the others will keep the tank running properly.So if you don't require a whole tank controller, but want a top of the line temperature controller, this is it. Even if you don't want to shell out for this one, you need something monitoring the heaters. Just don't be surprised if you go with a cheap Chinese controller and it fails after 2 months.After you get past the price of this unit, you will be so glad you got it.