I have a 125 FOWLR up 19 months. My water parameters are good (8.3 PH, 0 Ammonia, 0 Nitrite, 1.025 SG and 78 degrees tem) except for Nitrates which run 40-80. Are these levels a danger to my fish and how can I lower them? My fish are all fairly small and include 2 Heniochus Butterflys, 2 Ocellaris clownfish, 1 Klein's Butterfly, 1 tiny Yellow Tang, 4 Green Chromis and 1 Flame Angel. I have 80-100 lbs live rock, Fluval FX5 cannister filter which I religiously clean out every Sunday, a Submariner 9 watt UV, two Coralia 3 and one Coralia 2 powerheads and another powerhead that sweeps the surface. I only change about 10 gallons every week when I do the filter clean out, but it's every week and I use RO water. I live in a highrise apartment, so I can only store about 15 gallons of water. I've tried a couple of products like Algone and De-Nitrate with limited success. I try not to overfeed, but probably do a bit. Anything I can do to get the nitrates down?