I posted a reply to another thread on this topic. Did you post it more than one time?

Anyway my first question is what is your phosphate level in that tank? Phosphate can have a lot to do with the formation of that particular plague. You may need something to get rid of the phosphate if it is off the chart first like a phosphate removal pad to float in the water and then the Maracyn can be used. I have not personally used it for that but I have used it in very high concentrations for a stubborn fish infection at the manufacturer's recommendations due to extremely hard water and it did not hurt my biological filter at all. I did remove all carbon from my tank so I did keep close check on my phosphate levels during the treatment as it was used for 15 days instead of the regular 5 with 50% water changes every 5 days to assist the fish.

I do not see a problem but I would be checking for the phosphates first as if this is the problem, you will need to be getting them under control or the algae will be right back.

Rose