Just joined this community. The information on you page has been very helpful already. We just moved to a new house with old pool and old tub, and the previous owners had used : "natural chemicals" and it has given me all kinds of grief trying to maintain clear water. Probably;y mostly having copper in the water. But I am learning so much from your site. I was getting all kinds of conflicting info from the stores. I just ordered my proper test kit and am excited to finally take charge of these water beasts. TY