Bro, the prism skimmer is like this, not very effective. I have used it at the start of hobby on a 3 ft. When I upgraded to 5 ft tank and used in sump skimmer like HS skimmers I find them more effective. Now coming back to hobby after a few years starting with a 3 ft again and looking around for a skimmer and LFS still recommended RS prism skimmer to be the best for hang on skimmer. lol