I replaced the skimmer with a larg refugium full of grape caulerpa. A refugium with caulerpa removes nutrients threw growth, you harvest about 2/3 of the caulerpa there by removing the nutreints and the caulerpa regrows removing more. The algae doesn't remove the micoscopic food or iodine that a skimmer does, that your corals need. Basicly the refugium of caulerpa removes the bad stuff leaving the good stuff for your corals. Skimmers strip the water of the bad and good.