Closed or weakly perpetual reservoir to clean once and for all is difficult. In any case, foliage and other organics will fall into it. Rockbrown, it will change the biological structure of water, giving food to small algae. In addition to cleaning the pond of garbage, it is necessary to use drugs based on aerobic and anaerobic bacteria. Biomag and microsim ™ “Pond Trith”, or any foreign.