I have 2 800 watt heaters, 1 is an aquatop with a seperate controller/1 is just the finnex TH with no controller for my 225 gallon. I want one as a backup.

I was thinking about using the aquatop with controller as the primary set to 78 with my Apex set to turn on at 77.2 and off at 78.3. The reason I want to do this is because I don't want the apex switching on and off all the time it will wear out the contractor. I would rather wear out the contactor in the heater controller, its much cheaper

then I was going to setup the finnex with no controller directly to the apex as a backup

But I can not have both heaters on at the same time no matter what, it will trip the breaker.

How can I program this?