hieght of overflow outlet

[bbreaux1]

how low below the water surface should outlets be that flow into the sump?

 

[squidd]

The outlet itself pretty much regulates the height of the water in the tank...
If it's large enough there will be about a quarter inch of water overflowing the pipe/box do to surface tension of the water...
If the drain/line is small the water will be slower and build up higher... if it's too small the water will overrun the drain and cause an overflow...
Unless I'm missunderstanding your question...
Are you asking where to drill the hole in the tank...??
Or perhaps the line into the sump...ie: above or below the sump level...(slightly below)

 

[bbreaux1]

yeah talking about sump level thanks

 

[shanev]

It varies. It is really up to you. I had to play with mine to help eliminate the noise from the water rushing down. Ending up going with it right at the water line with an L about 70% submerged.