I just had my pool installed. I am learning so much from all of you. I was talking to my pool builder yesterday and told him what I have learned on the forum about chemicals and the bbb method. His statement was exactly what you all have been talking about. He said " you can't believe anything on the internet. Also you can't buy cheap chemicals from Walmart or the internet because they are garbage and not as good as what he sells. I didn't bother arguing with him but you guys are right about these pool store owners.