When we had high metal we treated for that while not letting the chlorine fall too far or we would be right back in the green again. I would treat for the metals as soon as you can - we use well water too so will treat for the metals immediately as we top off each year so that we can stay ahead of the chocolate brown we end up with if we don't. We have to get the chlorine level up there and keep it that way or the algae gets out of control - its a delicate balance!