I am learning alot from this site!!!!!! the pool store owner even told me dont worry about my cynaric acid level cause it is city water. I cant find my results and will go back on saturday. Does anyone know how much chlorine and how often I add to my pool to keep my level up? again, its 70,000 litres and its inground and vinyl. Is it o.k to swim if my chlorine is at 5? my kids are going nuts.................