this would not be a good idea because if the power went out, the siphon would break on the u tubes if there is no chamber on the outside of the tank to keep them full of water. then when the power returns, the water would pump back into the tank but would no longer drain thru the u tubes - translation: overflow tank until sump is emptied and then burn up return pump because it is running dry.

Quote Originally Posted by Justahobby View Post
I've been curious as to if the pressure of water flowing against the sump water slows the overflow box down ie. exit pipe in deeper/ larger water volume slow the exiting water.

Couldn't you drain the tank down several inches, attach a calfo, and use u tubes connected to hoses without messing with drilling? That should achieve the same effectiveness as far as surface skimming is concerned. Just an idea.