Return Pump Kill Switch?

My overflow is also gravity fed.

I don't have chambers. It is only a 20 Gal. rubbermaid sitting beside my 55 Gal tank because there is no room underneath. I had my skimmer in the main tank and had to get it out of there so I just moved the skimmer and return pump to the rubbermaid and set up the overflow. I was thinking about raising the return pump up on some kind of platform so it could only pump out a third of the water in the sump but was going to go the sensor/float route if I could.

 

If you have a controller, I would stick with a wet sensor. That way, you have no moving parts to fail, and less room is taken up wherever you decide to put this.

I know on the RKL and RKE, that means pretty much just a pair of wires run from one of the switch ports up to the "just before overflow" level of your tank, and the open ends left close enough together. You might want to add something that won't corrode or oxidize (like titanium) to the tips of those wires and seal them up, so you never have to clean them (and there's no copper accidentally entering your tank), though.

 

I was thinking you could use a float switch upside down, so only when the water level exceeds a set spot the switch would be activated and shut off the pump????
Like the reverse of an ATO switch...

 

Yeah, you could. But an ATO is bigger than just the tips of two wires, and I was specifically mentioning it for the controller.

 

Float switch in reverse?