After dumping large amounts of shock, buying a bigger sand filter, putting "green to clean" to get rid of Swamp in our pool the algae finally sank to bottom. We started vacuuming on waste to just get rid of the algae instead of filtering it. When putting filter on waste position, some of the algae was coming back into the pool through the jet! I did not think water was supposed to be coming back into pool on waste position. Is our brand new filter not working properly?