Ok so I opened pool filled it up and have clear water.....pool store told me to use three bags of dura shock to open based on pool size (a/g 27 round).....shocked pool and next day strip shows no chlorine. sample brought to pool store shows FC .12 ppm - TC .45 ppm - CC .33 ppm - PH 7.2 - hardness 85 ppm - alkalinity 110 ppm - cyanuric acid 20ppm. Pool store said may have chlorine lockout and to put more bags in so I added two more bags of dura shock and still no reading on strips......please advise as to best course going forward. Thanks!