in my opinion, ill agree with some of the above threads, the myacin, will do damage to your benificial nitrifing bacteria. i found in my tank it was a watter quality issue. first are you on city water or using ro/di? have you all tested for phosphates. this is where i found my problem with the red slime. when i first started in the hobby of marine fish and inverts, i used city watter, where i found high phosphates. the cyano feeds on these phosphates. the lfs i worked at at the time had the same problem just not as bad as was happening in my tank, they were using ro watter, guess it wasnt getting all the phosphates out as well. i found a good PO4 test kit and some phosphate remover fixed the problem. and when i moved and got on well water. no more phosphate problem at all! ide test for that first and fix the nutrient problem by removing it if you have it in your tank. this will help with other unsightly bacteria problems returning in the future, and also help in not hurting you benificial nitrifing bacteria colony. look at it this way too. if you were to loose something in your system from the myocin. and not catch it, you would start your whole cycle again, and cause furthur undue problems and possible loss of other livestock. just my .02 cents and my opinion.