The limitation of a large sea anemone tank with seagrass as breeding ground (for all kinds animal), the most efficient nutrient utilizers will dominate. Seagrass bed is a wonderful way of filtering out organic matters, see the picture differences of the same tank below. The same camera and settings, one with macro mostly(before) and now with seagrass as the dominant plants. Do you notice of the clarity of the pic with grass bed vs the macro dominant? It kept ph, PO4, NO3.... in perfect range even without a skimmer, hence the accelerated growth of the grass bed.