Ever since I replaced liner/sand in the middle of last season, water clarity has been a problem. Ten years prior, no issues. Nothing else has changed, except this year I purchased a TFT kit. All the numbers are within range. The water slowly turns a greenish/yellow(cc is zero). All other numbers remain the same. I'm adding DE to the sand. Doing this 3-5 times a day clears things up dramatically. I skip a couple of days of DE and we start to turn again. Using BBB, even after shocking nothing clears up. Only after DE addition things get better. is it possible I have bad sand? I removed and rinsed/cleaned sand from filter a couple of weeks ago. Laterals and center pipe looked fine.