The reason the free chlorine levels need to be low is that the chlorine will attack the metal control and use it up before it can do the job. It won't hurt anything but your wallet . I know it is hard when dealing with metals - because it is frustrating. But szampino is right, most of it is having the patience to let the chemicals do their job. It is easy to try to fix the water by adding more and more things, but it destroys the whole balance. Adding something before what you added first can do it's job will only make clearing the water take a lot more time, and use up a lot more money. Simple is best, less is best. Patience is the least expensive, but the most difficult part of clearing a pool