WC causes skimmer to overflow for days

[e46er]

So i got a new used skimmer a vertex in280 a few days after the new year I got it dialed in i have a hose with a ball valve coming out of the cup drain. and then did a WC and then it goes nuts and its a constant flow out the drain for days until I readjust the skimmer and its working properly.
Do another WC and same thing it goes nuts and runs for days overflowing.


what would possibly cause this?

the skimmer shuts off with the return pump so the change in sump water level height when the return is off doesnt matter and it stays constant when operating.