I love my ghost skimmer. I guess I’m just lucky. It does everything it’s supposed to do and it’s actually made for our nuvos. I think it mostly comes down to tuning and patience. After the initial two weeks breaking in it has worked perfectly.
On another thought, a protein skimmer does not constantly produce skimmate every single day. Sometimes people assume that it’s not working because they’re not seeing foam and don’t realize that maybe there just isn’t anything to skim in the first place, especially if you have mechanical and chemical filtration in front of it. My water passes through filter floss, chemipure, and matrix before it gets to the skimmer. Along with my water changes and light fish load (pajama cardinal, tailspot blennie), the amount of organics dissolved is light. Research realistic production of foam from the different skimmers and you’ll get a better understanding of what I’m saying. Melevs reef and Mr saltwaterfish on Youtube have really good videos on the subject.