Overflow / Sump Issue

[burblecut]

Sure, I'll post a pic after work

[lastlight]

Sounds like siphon is established which drains super fast and then air gets in there until siphon is established again. If you have two holes drilled I'd run a herbie style overflow. Gate valve on the lower standpipe valved to match your pump's output. Taller emergency standpipe that can also handle the pump's output should your main drain gt plugged.

[mark]

are you running a Durso or similar type drain (Hofer, Stockman)?