I'm starting week #5 on vinegar dosing. When I started my NO3 was >64 and PO4 was <0. I did a water change earlier today and just finished testing and there is absolutely no change NO3 >64 and PO4 <0. I have a 40 gal. system (30g with a 20g sump) and have been following the dosing charts found online rounded up to make it easier. Am I doing something wrong? Shouldn't I have seen some kind of change? How can I have 0 PO4 and ridiculously high NO3? I use Red Sea test kits. Any help or recommendations would be appreciated.