So, I have always done regular water changes in my 180. During the past year my skimmer has pulled very little. Contacted MRC and have come to the conclusion that my refugium is working efficiently. Nitrates stay at 10 ppm. Since trace elements aren't a huge concern with a FO tank, what should my water change schedule be? If changes are to primarily export NO3 there isn't much reason to do big water changes. I add calcium/purple up for the LR. thanks tommy