Is a full strength, concentrated algaecide that is compatible with the Biquanide system. In order to keep algae from the point where it becomes visible and unsightly, it is necessary to maintain a level of Oxy 50 in the pool. A weekly maintenance dose helps to prevent an algae bloom. OXY 50 ALGAECIDE QT - 12/CASE PHOENIX 50% QUAT ALGAECIDE