I look at the tank and see so much progress. Lps corals doing great. Fish growing, including mandarin. However, battling cyno, some rocks, but sand is covered 70%. Tank is 8 months old. 73 gallon plus 19 sump. This started 2 months ago. Phosphate..03. Nitrates about 5ppm. Ready to try chem-clean? Experience using chen-clean???? Advise?