Protein skimmer blues Red Sea max 250

[Surfrat]

I purchased a Red Sea max 250 off Craigslist that I got a great deal on I think at $450.00
It came with all new fresh t5bulbs and has worked great with the exception of the protein skimmer. This is the older style max250 with the protein skimmer that came in the package set up.
I just can't seem to get it dialed in without constantly adjusting the skimmer gate to control water level in the back. I need to install a top off I'm guessing but I can't believe this has such small tolerance to run properly. I've checked the impeller and it looks good.
Any and all suggestions are welcome

 

[Amboss72]

Buy the largest wood air stone you can along with a good air pump. Make sure you purchase a wood air stone as they produce much smaller bubbles. Place the air stone inside the skimmer body and you'll find you consistently have better quality skim. The skim may just build up on the neck of the skimmer so keep that in mind when it comes to cleaning. I would also recommend replacing the wood air stone every month or so.