Some background first: 1. I purchased a used RS 170 Aquarium for a really good price (Good!) April 28th system start date, however the system has been running since November, cycled. 2. It came with the following livestock (good and bad) Yellow Tang Kole Tang Scooter Dragonet Lawnmower Blenny Bluespotted Watchman Goby Ocellaris Clownfish ___ Peppermint Shrimp 60 lbs of TBS LR Candy Cane coral Some zoanthids Acropora (Bali Slimer) Duncan Coral Sponges various sp. 3. I've upgraded several pieces since aquiring this system: 1. Vortech MP40s 2. Vectra pump 3. Aquamedic dosing pump (4 heads) 4. Reef Octopus 150SSS Classic skimmer 5. Radion XR30W Pro fixture 4. Since moving the tank, and setting it up in my home, the Nitrates have basically been off the chart. Readings: N03 = 100 ppm Salifert Po4 = 0.0 Salifert CA = 500 ppm Red Sea Alk = 9.001 Hannah Mg = 1350 Red Sea SG = 1.026 PH = (varies from 7.90 to 8.1 with carbon dosing) 5. I've done two 15 Gallon water changes in a week as the corals and fish didn't look so good, I was orginally intending to control N03 with carbon dosing, and pursue GlennF's DSR method. However, the livestock was suffering. Hence the two water changes. Everything looks much better now, but the result of these changes are absolutely no dent in NO3. 6. I started dosing Vinegar on May 10th and I started with 4 ml daily. Every week since I've upped the dosage. I'm currently at 56ML daily, dosed in the daylight hours 9 times a day. I have bacteria strings in the sump, nothing in the display, and the skimmer picks up about 50 ml of dark gooey stinky skimmate daily. Obersvations and Changes: 1. It's likely my N03 is over 100 ppm, that's really the only variable that could have possibly changed when doing a WC. The Candy cane stopped receding, the Duncan doesn't seem to care about N03, and the Slimer stopped receding. 2. The only livestock I've added since acquiring this system was a small pistol shrimp and a feather duster, both doing fine. 3. I feed one cube of Brine/Mysis/Mystery mix daily in hopes to increase my P04. This has not changed. 4. I've vacuumed the sand thoroughly each WC, and removed about 15 lbs of LR. And there is still too much in there for a tank this size. Next Steps: 1. Does Po4 limitation in any way inhibit the effect carbon dosing has on Nitrates? I've seen some threads regarding adding Po4 to a system that's devoid of them but have no idea if it works regarding Carbon dosing with vinegar. 2. I was thinking of increasing my Vinegar dosing each week until the N03 drops, then pull back to a maintenance dose. 3. I'm not adding any livestock until I get this under control. 4. I've been dosing Vinegar for approximately 5 weeks. Thoughts?