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Are you refering to cynobacteria? If so, there is nothing that will consistantly remove it. I suggest soing a search on this site for cynobacteria for some in-depth answers.
In a nut shell...it thrives based on excess nutrients in the water. Mainly PO4
. First, test your tank and source water for both of these. Next, manually remove as much of the cyno as you can via siphon and do a water change using good quality pre-mixed RO
water. I am not a fan of using additives or chemicals to deal with water quality issues, however, in this case you might consider using a product called Chemi-Clean to help rid the tank of the cyno. Keep in mind, this will only remove the existing cycno and will do nothing to keep it from coming back. You must ID and correct the problem for long-term success.
Consider the following:
-water change schedule
-food offered and feeding schedule
-age of the bulbs
these can all contribute to the cyno issue.