[Rcpilot]

If you leave the water level low enough in the sump and refugium, then it can't flood. Once the tank level drops enough to stop the water from flowing into the overflow box, it's done filling the sump and refugium. As long as there is enough capacity in the sump and refugium to absorb that display tank water until the overflow stops, the sump and refugium will not overflow.

So, you adjust your overflow box at the right height in the display tank so that the water level can't overflow enough to ever fill the sump and refugium. The siphon overflow gets stopped as the tank level drops before the sump and refugium ever fill up to flood point.

You have to have the baffles in the sump and refugium set at the right height to absorb, maybe 4 or 5 gallons when the power fails. The refugium is 10g and that wet/dry is probably 10g. Thats 20g total capacity. If you run them both at 50% capacity, you'd still have to siphon the display down 10g to make it flood in the sump/refugium. By the time you get 10g out of the display tank, the water level will be 2" below the intake for the overflow. Can't happen.

The powerhead can't siphon anything. The discharge pipe from the powerhead goes up higher than the sump or refugium. Even at full capacity. Water cannot siphon uphill without some assistance. And if it does, it's going to continuously siphon from the sump--into the refugium--out the powerhead--and back to the sump. Can't go anywhere.

When the power starts again, the sump pump is going to suck the sump down to normal level much faster than the refugium powerhead can pump the refugium dry and fill the sump to the overflow point. When the tank starts to fill from the sump--it will eventually reach the point where it starts the overflow again. If your siphon didn't break-- you're back in business. Water levels in the sump and refugium drop back to normal levels.

So, why doesn't it work? Not being a smarty pants. I really don't see why it won't work. If somebody knows, please tell me. I'm a newb.