I like to keep a slightly “dirty” tank for SPS and to do that I rely on a high import/export system. I target 2 to 5 ppm for nitrates and .03 to .07 ppm for phosphates.
On the import side, I like to keep a good number of fish and feed them heavily. I believe fish poop is beneficial for corals. For export there are a few things I plan to do with this tank to keep nutrients in check.
Export Road Map
One is to use macro algae, a natural means of exporting both nitrates and phosphates versus using a chemical such as Granular Ferric Oxide (GFO). GFO can bind not only phosphates but valuable trace elements as well.
Another downside with GFO is that it will not export nitrates, just phosphates. GFO can also shock SPS and cause them to stress out and fade if used too aggressively.