I have been running gfo for about a year now at 20 tbs every 2 weeks in my 90 gallon mixed reef. My nitrates have been slowly rising while phosphate is almost 0. I was thinking of ditching the chateo and gfo and going to biopellets. My question is about how much do u think I'd use and how often do you change it out. Trying to give myself a little idea on the cost xcomparison between gfo and biopellets plus maybe moving from a 15 g water change every 2 weeks to 20 every month with the biopellets