Had cyano so bit the bullet and treated with Chemiclean. Followed the instructions. Turned off skimmer and carbon reactor for 48 hours. Did 20% water change, turned carbon back on for a few hours then skimmer. Got gate valve all the way open and skimmer is still overflowing. Read some posts on RC the it may take another 20% water change and carbon change to get my skimmer to work again.