I've had an IG pool fro 3 years now and never had a problem holding free chlorine, this year has been very different. My water is clear and all of my other levels are fine but my TC and FC levels are zero. A pool store employee asked me if I had a lawn service and if I do he thinks some of the overspray could be locking up my chlorine. I started having my lawn serviced this spring (weed and feed spray) so I'm wondering could this be the reason my FC level is always at zero? If so why is my water still so clear? I also had my trees sprayed this spring.