Calibrating Dual Heater Setup

[RPMick]

Got a 75 gallon tank with two 250W Jager heaters running horizontally across the bottom of the tank. Calibrated both heaters individually to 81 degrees but when used together, the heater on the left (closest to the filter output) is a clear workhorse and the one on the right hardly comes on at all. I'm assuming it's due to the fact that the water output is persistantly triggering the closest heater but my water temp (being taken front he front right of the glass) is sitting at about 82 usually. The house sits at about 77 degrees when people are here and 81 when we're away during the day.

My thoughts were to have the two heaters sort of load balance but that's just not happening. Considering moving that left heater to a vertical position between the input/output of the filter to heat the input water better and leaving the other one across the tank in the horizontal position but not certain yet.

So my question for those of you that run dual heaters, did you calibrate them individually and do you have the same situation where one of the heaters carries the load for the entire tank? Am I over complicating this and should I just start thinking about the less utilized heater as a backup?

Link to a crappy picture to better illustrate the configuration: https://www.dropbox.com/s/w2b52gfifx608jc/Photo%20Sep%2013%2C%207%2022%2011.jpg?dl=0
Hard to see, but the filter output is vertical and to the right of the filter intake.

Thanks!

-Ryan

[wild4discus]

It's nearly impossible to calibrate both heaters to come on and shut off at the same time regardless of water flow or positioning in the tank. If one heater is able to maintain the temp you want, I would keep the other one as a back up. If you want to use both to reduce the workload on a single heater, use a good quality temp controller and that will solve your problem. No need to calibrate heaters, just set them a few degrees above the temp you want, set the desired temp on the controller, plug heaters into temp controller, and you are good to go.

[ericNH]

So THATS what a temp controller does! It shuts off the power to your heaters when the target temp is reached. I think I get it now. Set both heaters to maximum, and hook them up to a temp controller. Is that right?

[farebox]

I been using an ETCI-1R20A (wired), ETC1Ra100p1, Electronic Temperature Control w/ 2 Receptacles for up to 2400 watts load. Requires 20 amp twist lock style wall receptacle. Includes digital temperature display, Ready to use with heavy duty 12 gauge x 6.5’ long power input cord -L5-20P and 2 x 3-prong grounded receptacles. 1000 watt one side 1400 watt second side. $125.00 from JEHMCO.com.