Hi all!!.. I have a boyu TL-450 with a boyu 308 protein skimmer with about 4 kilos of live rock and 2inch deep live sand. I have 2 false perc clown fish, 3 hermit crabs, some snails, a tuxedo sea urchin, frogspawn and zoas. My nitrate level is at 10mg/l but i cant seem to lower it even if i do a...