Overflow box sometimes drains. Help?

[Warpigdave]

I have an overflow box and I’ll dial in the ball valves so the level is about 3/4 up the drilled bulkhead openings. But occasionally it will just drain completely. Then it will fill and run smoothly and quieter again. It’s a bit annoying to keep dialing it in. My pump is a constant speed. So maybe an adjustable return pump will help? Any suggestions?

 

[BanjoBandito]

Is it a single tube drain? Sometimes when it's asked to move too much water it'll glug some air and it'll do funny things. Do you have a durso style drain (air hole) installed? I'm going through some sump trouble shooting at the moment so I'm in my "HYPER AWARE MODE" for this stuff. lol. Let me know what ya figure out.

 

[Warpigdave]

Is it a single tube drain? Sometimes when it's asked to move too much water it'll glug some air and it'll do funny things. Do you have a durso style drain (air hole) installed? I'm going through some sump trouble shooting at the moment so I'm in my "HYPER AWARE MODE" for this stuff. lol. Let me know what ya figure out.

Its 3 drains. One of which is an overflow. Not durso.

 

[Dburr1014]

Have you tried to replace the ball valve with a gate valve? Ball valves are a little finicky where they gate ones you can really tune in

 

[BanjoBandito]

Its 3 drains. One of which is an overflow. Not durso.

do you have an emergency drain line? Sometimes when you aren't taking minimal water through the emergency it can cause an overflow flush. Can you post a video at all?

 

[Warpigdave]

do you have an emergency drain line? Sometimes when you aren't taking minimal water through the emergency it can cause an overflow flush. Can you post a video at all?

Sorry I meant I have 1 emergency drain line out of the 3. I have it not taking water.

 

[Dburr1014]

Oh, i see. You are not going full syphone keeping it 3/4 up the driled bulkhead. With the ball valve, it is tough to tune. You need a gate valve and tune the main to go full syphone with a trickle down the emergency. This will fix it.
Edit: the gate valve needs to be close to the sump.