Help with skimmer

[geweagle]

hello everyone,

I am very new at this so any help would be appreciated. I have a 2-month old system. Bought this skimmer second hand. I was told it is very good. I do not know its name or have any instructions. When I started using it everything was great. The cup filled in about 1 week and was dark and smelly. I understand that is good. Now all of a sudden it is filling in 1/2 a day. The liquid is lighter and watery. Not know what changed. I am working to get PO4 down. it is at 1 ppm now. as I try things I find the outlet flow control knobs (2) on the front. I have them at max flow. If I slow them down the cup fills up with water. I tried decreasing air flow, seems like lots maybe too much bubbles. That also made the cup fill up in 1/2 hr. So I do not know what happened or waht to do. Any ideas would be great