Can someone guide me how to achieve Crystal Clear Water? I have a 72g with a sump. The water is clear but still there are lots of tiny particles that float around. I read that even a system with a sump can benefit from an additional mechanical filter which helps remove those tiniest particles that are not caught by the sack in the sump or by the protien skimmer. If so, what kind of filter is that? Can I get something that fits in my sump?