Gate valve

[Palting]

Thanks I didn't even think of that. But will the durso standpipe setup still work with no overflow box?

Yes, the durso will work with no overflow box, but half of the upper arm will be out of the water. Here's a photo of the classic Durso:

 

[AZDesertRat]

Look up Maggie Muffler or Maggie Muffler Mini. Its basically a readymade Stockman standpipe cap that works quite well and is very unobtrusive.

 

[gcrawford]

Might want to look up the "Herbie" method which uses two drains, one of which does use a ball valve or a gate valve adjusted to make a full siphon on one drain at sump water level, with the second drain as a fail over if needed and has a very small trickle of water - practically none. I use this with a lifereef dual overflow and it is totally silent.