ok thanks for reponding,tank params are cal 500, nitrates 0, phosp o, dkh 11, sg 1.025, temp 79. so far i have replaced all light bulbs, pulled back all supps except, kalk mix, and 2 part cal/buffer. waterchanges are 10gals biweekly and for about 4months 15g biweekly, added 2 more powerheads for more flow, added mangroves and cheto. and still algea. have taken all rock out and scrubbed clean. switched to bare bottom system and still algea. i believe the work to be leaching phosphates. i also use phosban phosphate remover.