Nutrients aren't the same thing as nitrate and phosphate. soft corals and LPS corals enjoy being "fed" with phytoplankton, rotifers, meaty foods such as mysis and enriched brine. Of course, all that food breaks down and has to be removed through your filtration - protein skimming, scrubbers, chemical filtration medias. SPS corals feed indirectly off of the waste of fish. Feed your fish what you normally would and in turn, SPS corals also feed off of whatever nutrients is left in the water column. HOWEVER, SPS corals do rely on photosynthesis in their zooxanthellae more than their predatory instincts to capture live foods and organic matter from the water column.