Originally Posted by Kube
http:///forum/post/2835308
you are absolutely correct in the fact that when the power goes out the overflow box will only allow the tank to drain so much, just have enought room in the sump to handle the excess
when the power does go out the u-tube stays filled with water. they are designed in a magical way that they don't drain the water out (lol...i can not explain how it works, beyond me, has something to do with pressure on both sides of the overflow keeps the water pushed up into the u-tube.
I think if you had a small hole that u-tube would drain, and would need to be primed again, this has to be done manually by inserting a small airtube to suck the water out.
once its primed it never looses it prime for the most part, i stop my return pump daily to feed and the u-tube never looses it prime
so when your return starts up, water overflows into the box and push the water back up the tube over the u and down to your sump
I have seen many diy cpr style over flows that have the nozzle drilled on the top to suck water out, the advantage of the u-tube is you dont have to have that aqualifter pump running, because if it fails you loose the siphon and you have a flood, just one less thing to worry about about
i'm no expert on this, did alot of test runs in the garage with rubbermaid tub to see what would cause a flood
also if you had a whole in the u-tube you would never be able to prime it correctly because as you sucked the air air would return through the hole
Ok, you win. I forgot about the magic holding the water in my thought process.