Answer:

Green hair for swimmers is typically a result of metals present in the swimming pool (also reacting with other pool chemicals present). The most common metal to cause this issue is copper. Use a metal agent to remove the metal from the water and you should see this problem go away. PS - the copper may be coming from the heat exchanger (if you have a heater). That would mean that you have corrosive water and need to determine the source (maybe low pH).