Are my heaters working properly?

[fishfrenzy]

I have 2 200 watt Rena heaters in my wet/dry filter (20 gal in size but only less than half of that is water) for my 135 gallon tank. Room temp is 64 deg F. There are 2 problems. One is that the temp in the tank is 82 deg F but the heaters are set much higher than that. The other problem is that the heaters are off sync. I had to adjust them differently to try and get it right, but still having problems. The one set at 85 is constantly on which I guess keeps the tank water at 82. But the other one set at 88 only turns on when the tank goes to about 80 and when this happens, the other heater (set at 85) is blinking which indicates that the water temp is too low. So why is the heater that is set at a higher temp turn on at a lower temp than the other one?

As far as the tank water temp being at 82 instead of 85-88, would it make a difference if I placed one heater inside the tank instead of both in the filter? Or are these heaters simply too weak to heat up my 135 gal tank? When I purchased the heater, the box said that a tank over 90 gal requires 2 200 watt heaters.

[Eddie]

Most heater manufacturing companies dont take into account the elevated temperatures that discus are kept at. There is such a broad range of temperatures for different species so 2 200 watt heaters in a 135 would probably be about right. I dont really like the Rena heaters, never have. Once I switched to Eheim Jager, I never looked back. If you have the money, get a 250 Jager and keep the other Rena as a spare. You'll be happy with the results. Alternatively, the Hydor inline heaters are pretty popular so you may even decide on that route.

HTH

Eddie

[scottthomas]

I would add that most times putting two heaters in is not very efficient. Always seems that only one is always on. This is because t.he set points are a little different and almost impossible to syncronize them to both cut off and on close to the same time no matter what you set the temp at. I would get a temp controller that you could plug both heaters into. You will have no problems I bet. I have never been able to get two heaters to work together to heat a large tank. I do use two heaters in some tanks but one is a bckup in case of failure by the first

[Jhhnn]

I favor the Jagers, too. I also use the finnex hc-0800 controllers, rated at 800W, all from kensfish. Out of the box, jagers need to be calibrated in a spare tank or water barrel, which requires some fiddling. Once that's done, I set 'em to 88-90F, plug 'em into the controller, use the controller to regulate the actual tank temperature at a lower setting. If the controller were to stick on, the heater's internal circuitry should take over, prevent cooked fish. If the tank temp moves up into the 88-90F range, you'll know what's happened.

Normal recommendations for heater wattage are 3-5 watts/gallon, so a 135gal tank would need 2 of the 250W models, wired to the controller with something like this-

http://www.pcconnection.com/IPA/Shop...tm?sku=7711796

Jehmco and others sell pre-wired Ranco industrial grade temp controllers, which are excellent, but pricey...

Edit- the calibration on your rena heaters may be off- kinda seems that way from what you've offered...