If you can, post an actual CYA reading. Also, any idea what the CYA was upon closing last year? Sometimes CYA is converted to ammonia over the winter which can cause a high chlorine demand upon opening. You just have to keep hitting it hard with bleach until your pool holds chlorine. We actually see many posters with this problem in the spring and they feel like they will never get enough chlorine in there to actually hold. Sometimes it can take gallons upon gallons upon gallons to the point where you think the problem will never rectify itself and then at some point it does. Keep shocking . It will eventually hold a FC reading. Keep us posted how things are going. And, don't worry about the strange looks you get at Walmart when you buy buggies full of bleach!