Hi.\n\nI have in my 75gl two corals. One is the Zoanthid Button Polyps and one is the Colt Coral.\nThe Zoanthid Button Polyps in my tank for 2 months, it is more colorless now and i see that it is being lost almost half of it's polyps.\n\nI have 2 questions:\n 1. I just read about the activated carbon, that it can harm the corals. If it is true how should i filter my water with something else?\n 2. How do i improve my corals to be always colorful and growing?\n\nThank you.