sumps using hang on overflow

[andsoitgoes]

I have a 600gph overflow being pushed back by a MJ 1200 to about 4' head - never a problem. The overflow will adjust to the speed of the return

[bsyoun]

A second overflow box would provide extra insurance, in case the siphon breaks on the other box, but I don't think this is very common if the overflow is designed/set-up properly.

If the noise from your overflow gets too loud, you can set up a Durso standpipe (http://www.dursostandpipes.com/).