Overflow box not siphoning

[Johnny Reefer]

Originally Posted by TheReefGeek

Sure it can, just make the drain section of your sump small enough that your tank can take the extra water without overflowing. This would be flood-proof in my mind. ....

Well sure...in theory. But I think for most of our systems that is impractical and undesirable. My sump is a 33 and I figure it's got net 25g in it. I want to put a skimmer in it eventually. If it were any smaller this would be impossible. Also...with 25g of water in there would mean that I would have to have the 180 main tank water level about 4" from the top of the tank. Somewhat aesthetically unappealing. The overflow box(es) would have to be lowered that much further down into the tank, as well, in order for the water to flow into the box(es).

Cheers,