Never had this problem before and its only my sand bed not my LR. I sifted my sand with my fish net and my sand was back to its normal color but, a couple hours later reddish algae started showing up again on top os the sand Kessil 350a Blue light 90% white light 30-40% ammonia & nitrites 0 nitrates 0.00 ph 8.1 1.025 thanks P.S. I know you guys will need more info just let me know what you need to solve this problem