210 gallon system. Soon to be 1 year old. Started with 40 lb of TBS sand and 60 lb of TBS rock with lots of dry sand and rock. Phosphate typically between .2-.4, nitrates have settled at around 40 ppm. I find that my alkalinity consumption goes down significantly when my phosphate is above .4 so I maintain it there or a little lower. No water changes except when the sump get gross and I have to clean that out.