Gah. I hate that people paint pools. I bought a house that had a pool that was painted when I got to closing on it (long story). Are you seeing any blue color in your filter medium? Open up your filter and look in it for blue color. If you are, then I think you REALLY need to think about how you want to handle the paint situation. Maybe you got lucky and got a good paint job, but those seem to be few and far between.