I'm trying to figure out why the pool store, knowing that I had a 0 stabilizer reading and 0 free chlorine reading, would instruct me to add 12 cups of pool shock every three hours until I got a chlorine reading ... but not recommend that I add stabilizer first? This comes after bringing them my water, which clearly showed no stabilizer at all. I went through an enormous amount of shock, at a cost of $170, and THEN they suggested I add stabilizer and shock again. (It still hasn't done the trick -- but at least I got a chlorine reading after the stabilizer.) Granted, all that chlorine did make my water turn sparkling clear. Was that the purpose? I'm a new owner of an IG, chlorine pool, trying not to feel taken advantage of by the nice people at the pool store.