We recently bought a SWP 16K gallon Pebble-Tec pool. It appears pool maintenance was minimal. Calcium chunks on the tile, streaks on the bottom of the pool, etc. So I head to the local pool store with sample and enter the water test, buy chemicals loop. Two weeks ago, samples were taken to two competing pools stores and one measured the total available chlorine at 3 and the other store measured 10+. My own test kit measured 10+. So lesson learned here was: glad to find this website and be in charge of your own pool chemistry, Thanks for all the input and looking forward to becoming a junior water chemist.