I have a 46 gallon Bowfront with a cyano problem, and to a lesser extent some hair algae. I have been running a protein skimmer (reef octopus rated for 150 gallons and have a good sized refugium with Chaeto - lights on at night only. One week ago I took all the liverock out, cleaned them and put in a deep sand bed (dead sand). I know I have made a lot of changes recently and maybe I just need to be patient, but should I add a GFO reactor? If so, how much GFO for my system? How often should I replace the media? I have heard that GFO can have some deleterious effects? Any help would be appreciated.