My fish only tank tends to run about 100 PPM Nitrates or more (test only goes that high - Salifert), after a water change about 50PPM. I have about 600 gallons of water, filtration inlcudes: - 120W UV - 20 x 20 x 15 of bioballs and a gallon of Marine Pure balls - 4 of the big blocks of Marine Pure in sump - Running 2 x Reef Octopus 1000SS Bio Pellet Reactors - Running 2 x BRS jumbo reactors with Rox carbon and GFO - Reef Octopus 8000 EXT skimmer I do frequent 150-180 gallon water changes, every 2-3 weeks and my nitrate levels still seem to creep up. I feed probably 5.5 days a week, and I wouldn't say super heavy...I have dialed that back. I don't want to keep doing bi-weekly water changes. Any ideas? On my skimmer, is it better to run more water with a higher standing water level in the chamber, and open the gate up more for more flow...or lower water level with more closed out flow? Do I need to run it 24/7? It gets cleaned once a week. Gets pretty dirty. I also have room, I cound add ATS or cheto. Would appreciate any insights!