Do you have a good test kit? If not, you'll need one. We recommend the Taylor K-2006 or 2006C (better buy) that you can get through the Amazon link in my signature below. In the meantime, pick up a cheap OTO/Phenol Red kit someplace (red and yellow drops). Post some readings when you get them. Tell us the ingredients on the tabs and the fresh n clear shock. Some chlorine products have some stuff mixed in with them that you don't want in your pool.