In Ground Pool, ~40k gallons, Pebble Tech, Intelliflo iQ60 SWG, RayPak 406 Gas Heater, Sand Filter, Variable Speed pump, seems to get alot of sun, but no debri. built in 2006. TFT XL Test Kit, with SpeedStir. Water from hose March.2017 used to fill FC=0, pH=7.2, CH= 375-400, TA=240.