ummmm, nitrates = aptasia? since when? . water changes will not solve your aptasia problem, over feeding will increase them but they can survive like any other anemone with photosynthesis. peppermint shrimp or scats work. scats need some room though. shrimp looks like the way to go. i have 4 in my 180 and after some manual removal they never came back, the shrimp handle them very well.