Yep, had some man made rock that I had for a long time . Had it in my sump 5 years ago . So, I thought why not put it back in . I did not clean it just put it In . Well, next thing I know my nitrates rocketed to 75. I have taken it out and cleand out the sump. It has dropped to 50 my phosphates are .07 i do not want my phosphates going any lower . I started dosing vodka i am at 2 ml. A day for a 120 gallon system that is not much . I am afraid my phosphate will bottom out before my nitrates drop to ecceptable numders. Any suggestions.