Be careful though, as this broad-spectrum antibiotic will eliminate your biofilter.
I second this as well. I constantly have cyano in my 16g of doom. I dropped 50+ ramshorns in there and it eliminated the bulk of it. Not sure if their waste produced the needed nitrates or if they ate the algae, but its the only thing that has worked at all for me. (tried maracyn, tried blackouts, etc). The maracyn caused a mini-cycle however, which was less than desirable.