Today I cleaned out my Coralife 220 protein skimmer and now it overflows in 20 seconds or less no matter how open or closed the flow knob is. I'm using it as a hang-on skimmer for my 75-gal tank.
When I installed it brand new about 6 months ago, it wanted to overflow but I was able to compensate by leaving the flow valve barely cracked open. Anything more and the collection cup would overflow in 20 seconds.
I'll try to insert pictures so you can see the set-up.
Thank you in advance for any advice you can offer