I have an HOB-XC. It does a great job. I would not run a saltwater fish tank without a protein skimmer, that's just my perspective. I usually run my skimmer for a day, then turn it off for the day. The cup usually fills up halfway in a day, that is a lot of waste is pulling out of the water. My phosphates are usually always at .25, even running my skimmer. I have a Marineland 400 filter and a Fluval 70 filter, I change the carbon filters once a month. And I have a Jebao WP-25 waveMaker. Of course I run my wave maker and my Marineland 24 hours a day. Like I said, I run my skimmer and my Fluval 70 filter every other day or for a couple days, then give it a days rest. I also turn both of these filters off when I feed the fish and corals. I just bought the tropic Marin balling method, I'm not sure I understand it yet. So if anybody has any advice for me let me know. I tried to do a 5 or 10% water change every week or every other week. My PH has been about 7.9, is that fine. Everything is doing fine in my tank accept my starfish just died, technically I think it's still alive but two of its arms fell off and turned into goo.