TRUCKOOOO,
I always adjust the gasket on the waste cup by looking at the amount of bubbles coming into the cup. Normally the base of the waste cup should be 1/8" to 1/4" below skimmer's water level. I don't like a lot of bubbles to go into the collection cup because more water is removed from the tank. I adjust the rubber gasket until there are thick foamy bubbles. Everytiome you make a water change, add water, or clean the collection cup you have to readjust the collection cup.