So we put up a intex 17 round 52 inch deep pool a week and a half ago. I had 2 chlorine tablets which was recommended for that size in one of those floating cabanas, also used arm and hammer clear balance in the pump. I just tested with just a cheap tester where you dip it in and match colors to see where you are. Everything is virtually exactly perfect but my chlorine is reading a zero? I added two more and tested again next day, everything perfect chlorine at zero. Now this pool will be coming down for the season in a few weeks, but also notice the ground is becoming a little slimy feeling. What do I do? Add more chlorine? Use shock? New to pools and never had to maintain them. Please help.