Sometimes there is something in the water that causes berserk skimmer syndrome. When I have a skimmer overflowing, I crank it up to get it over flowing faster. I have salt water at hand. I let the cup fill, empty it, add saltwater to replace and repeat. Usually after about 10 minutes of this, the skimmer settles down and I reduce the skimmers setting to normal. Any number of chemicals can cause a skimmer to over flow. My trick is just a simple way of removing most of the offending chemical. Of course, it might BE the skimmer and then this method won’t help.