Saltwater cleans tile floors really well.

The little hole you are supposed to drill into the return u-tube/outlet at the level of the overflow box grid does clog up with coraline algae and needs to be cleaned from time to time.
The purpose of the little hole is to break the siphon action at the level of the overflow box.
When you don't clean out that little hole, the siphon action continues all the way down to the directional spout.
That's only 2 inches but 2 inches in a 6 foot long tank equals a really large amount of water - enough to overflow the sump in which it all drains into.
I heard about this before but I tried it out tonight and I think I'll remember it for the future.
My family will wake up to a sparkly clean dining room though...