ok so i got a 90 gallon tank drilled with a 40 gallon sump i got this protein skimmer and not sure if it's working or not i have done everything messed with water flow air flow everything it's at the right height in the water it's making foam and got it to where it will take a hour or so to fill the collection cup up with water then start overflowing why is the collection cup filling up with water and not just foam it's been running for 3 days now night and day i just want it to work can someone please help thank mike

the air needle skimmers take weeks to get exactly right. if you have water in the cup try turning the air down just a little tiny bit just turn it almost to where you cant even feel it move, try that. When you have to much water that means there is not enough air, if there is no bubbles/water that means its getting too much air.

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What skimmer do you have and what is the water depth that you have it.

Sounds like your pump is to fast for the skimmer to Me!.
I would try to lower the intake of water and let the skimmer produce foam within the reaction chamber.. and when it is producing foam slowly tern the intake of water up so the foam can reach the collection cup.
Don't worry though most skimmers are a pain to get just right at first.

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Remember people the solution to pollution is dilution... weekly water changes!

Do you happen to use tap water with an additive like Stress Coat? That is common if you do as the chemicals change the surface tension of the water.
Its also not It will get a slime coat on all the plastic surfaces and eventually settle down.