My pool store indicates chemical levels are normal, yet pool is turquoise. I purchased a Taylor K-2006 test kit with the following results. Free Chlorine 3.0, Combined Chlorine .2, PH 7.4, Alkalinity 90, CYA 100, Calcium 100. I have a sand filter where I replaced the sand, and have had it running for 4 straight days. The pool started the season crystal clear, then suddenly turquoise. Any Help or Suggestions are appreciated.