I had the professionals open my pool this season. Water was crystal clear for about 3 weeks, but can't get the pool people to come back. I've taken matters into my own hands by replacing the Polaris 380 with a Dolphin 2020 and having the water tested at a pool store. After adding the chemicals purchased from the pool store, CL is low, Ph is OK, Alkaline is low and CYA is low - and I can't see the bottom of the 9' deep end. Pool is plaster, 40,000 gallons with DE filter and auto chlorinator using 3" pucks. Also, pool is covered for most of the day, filter runs 12 hours and temperature is maintained at 82 degrees. Help!