I've been battling cyano for a couple months, and am now getting on top of it (I think). Here are some of the things I've done: increased circulation (added another PH), reduced phosphates (added poly filters, and rowaphos), small carbon changes weekly, new filter floss a couple of times each week, reduced feedings, vacuuming front portion of substrate once a week, and stirring substrate a couple of times each week.

It hasn't stopped completely, but better maintenance has helped. I'm hoping time will help too, as some of the vets have attested to.

Steve