My tank has been up again since August 2020. We have 2 clowns and a lemon tang. We have a couple corals after several have died including my beautiful purple and gold torch. I did a water change Sunday, cleaned the sand bed well and cleaned our canister filter. Our phosphates were at 2.0 after that. Today I teated and it was between 2.0 and 5.0... The color was right between! How can I lower my phosphates?