Here in Michigan I close the pool around the end of August and open at the end of May. I always have such a green mess when opening regardless of adding algecide or not when closing. I had a thought and I wanted to see what people here think of this. If I purchase a submersible pump and use it to stir the water, what if I add a case of chlorine say each month after closing until the water freezes. Then do the same in March and April after it thaws out. I have a mesh cover I can peel back easy enough to add the pump and chlorine. Would this help at all? Thanks.