I have a dual stage so it can power a chiller or fans if it gets too hot.

The most common failure for heaters is in the on position. And with 2 heaters you have just doubled your chances.

I have one tank with a heater, and use my Apex to catch it staying on. The other tank doesn't need a heater, and my chiller keeps the temp under control.

Both tanks have a max of 1 degree F variance, which I think is pretty good.

I have 2 heaters hooked up through my Reefkeeper lite unit. The controller is set to turn on one of the heaters at 78.5 and will turn on the other if it drops to 78. The upper point on the controller is set to 81 in case of a stuck on heater. Keeps my temp solid at 79.

since the heaters are controlled by the controller, if you hit 81 it's because you have a controller stuck on or the room's super hot. shouldn't ever have to worry about a stuck on heater. they might fail that way but they are being used as simple on/off devices via your controller now. stuck on is ok.

The point I was trying to make is with a controller you have "more redundancy". You can set the thermostat on the heaters for a max setting and the controller for a max and min setting. If either were to fail closed hopefully the other would kick out.

"The average annual temperature of most coral reefs is around 82 to 84 degrees Fahrenheit (27 to 28 degrees Celsius)(see Table I and Figure 1), which seems to be the optimum for coral growth (Barnes et al. 1995, Clausen and Roth 1975, Weber and White 1976, Coles and Jokiel 1977 and 1978, Highsmith 1979). The commonly advised mini-reef temperatures of 74 to 77 degrees Fahrenheit (22 to 25 degrees Celsius) are stressing most of the animals unnecessarily and, in some cases, severely."

In addition to this natural reefs fluctuate in temperature throughout the day depending on current. Observations between 76-83 are very common, what are you basing your statement on?

Oh yes I follow you now. It would be a good idea to calibrate the heater's built-in max using the heat probe from the controller though as multiple heaters will likely not be the same and none will likely match the probe on the controller.

Interesting thread. I check my temps almost daily, I have 2 heaters in my 180, both hooked up to my Apex controller. Noticed yesterday, my temp sitting at 76.5. I have another thermostat and checked it as well, same reading. I had turned my heaters up a few days ago, obviously 1 is not working properly at all, but they were both on. I haven't received an alarm on either heater either from the Apex.

Hmmm, I had thought 25 was too low for a tank so I upped my apex to keep my tank between 26.1 and 26.5. It got really hot in my house a few days ago when it was sunny and the tank got up to 27.1 and I was freaking out. Now me-thinks I should have it set there.

No, 86 is quite high (but not fatal)...... For my tanks (20yrs experience) anything between 78 and 82 is perfect :biggrin: