I have a 225 gal BB tank,with 110 gal sump. Water parameters are PO4 0, NO3 0,calcium 410, Alk 3.34, Mag 1350. I do water changes every two weeks,using TM Pro,and RO DI water. The amount of water I change out is 50 to 80 gal. I have a super large skimmer ,with a 13" dia.X 48" tall reaction chamber . The pumps are three Sedra 9000 NWs ,and it is set up as a RC skimmer . I have a Mag 7 as a feed pump. My return pump is a Sequence Hammerhead.