I dose vinegar on a daily basis. My nitrates were around 2 and my phosphates were .01. I was having an issue with hair algae, so eventhough my PO4 was low I felt my rocks which were dry rock from BRS must have been leaching PO4 and was being used by the hair alge. My tank is 45 gallons and my sump is 20, but total water in the system was only 35 gallons. I started slowly with the vinegar as per the table I found on the internet that everyone was using. I reached a maximum level of 11mls/day. My goal was to eliminate the hair algae, as I started dosing the vinegar, my nitrate levels dropped to 0, but my hair algae was holding on. In order to feed the good bacteria you need a carbon source (vinegar), nitrates and phosphates. Since my nitrates were 0, I started dosing potassium nitrate (KNO3) at a rate to raise my nitrate levels to 5 on a daily basis. Each day I would take a nitrate reading which showed 0. So I would add the KNO3 to raise it back up. I stopped at 11mls/day only because my Duncan and frogspawn corals would not fully open. Over time the hair algae mostly disappeared except for a few spots. I am now dosing 6mls/ day. Duncan and frogspawn look happy. Nitrates are holding between 2-5 and I've stopped dosing the KNO3.