I'm really trying to figure out why you have a pump pumping water down to your refugium? But, anyway, what you need is the regular AT-1, not the pump saver. The AT-1 works on the principle of, when the water level is too low, it supplies power to a pump. When the water level is too high, it kills the power to the pump. Why not use this system in the opposite way it is meant to be used. If you place the sensor for the AT-1 above the desired water level, which would supply constant power to the pump. When the return pump fails, which hopefully won't happen, the water level in the refugium will rise to the sensor, which will kill the power to the pump. Just hook your pump from the diplay to the refugium into the AT-1, set the sensor at the desired "TOO HIGH" level, and when the water level gets to that point, it will kill the power to the pump. This is all assuming that the refugium is at the same height as the main tank. Otherwise you will create a siphon, and all this work and money will do nothing. The water will flow through the pump, if it's outlet is below the main tank level, causing a flood. If you refugium is below the main tank, you don't need that pump anyway. Gravity will feed the water down to the refugium, and the return pump will feed it back to the main tank. Does that make sense?