My pool guy tells me to drain. But I am too nervous for that, plus, water is water and with proper treatment it should be fine. I tested today, the water is a tad hard, but ph and total cl ok, but the FC near zero. cYA ok too. The phosphates 1000 ppb. So do I just need to get a good cl shock? And if so, which one? I think my pool is about 25k. It's roughly 20x 40 odd shaped with beach entry. Thanks!!