Overflow box empties to fast.
 

So I installed a overflow box with a bulkhead and and down facing 90 degree elbow. My overflow box empties fast, makes a gurgling sound, stops the input in my sump, water runs for a bit and the whole process begins again.
I only have a ball valve above my return pump but restricting the performance is a bad idea I heard because i butns out the pump faster. What can I do to fix this? Thank you

Do you have an air vent at the top of the stack?

It's capped now but I can drill a small hole in it.

Your gurgling sound is a full siphon emptying the overflow tube/box.

You must restrict the flow of water into the sump in order to stop this from happening.

Restricting the inlet of your pump will cause premature wear on pump but shouldn't on outlet side.

You simply need an air hole at the top of your plumbing. Don't restrict anything. Look up durso design, it shows how to use a hole with a valve. I don't use a valve myself, just have a small air hole in the top of the stacks (dual overflow pipes).

post a pic of the setup.

what he said

That was it. Thanks for all your help. So simple but effective.