I do a weekly water change.... The skimmer is not brand new.. Its actualy a used one purchased off of AJ77

If I can get it to pull some skimmate I will be happy. Maybe the tank is good and clean already but since I have alot of cyno I figured I may have a large quantity of DOC that my weekly water changes are not keeping up with.
This cyno is very frustrating

I keep on turkey basting the rocks and corals to keep it clear. But within a day its back.
I've read that using a slower PH like a Maxijet 600 or 900 would work better on this skimmer than the 1200

Any thoughts?
thanks
Chad