I've been trying to lower my TA and it seems like I am precipitating something out of the water. I think it might be Iron, but figured I would see if anyone here can support or destroy that theory :
CH 525 ( Phoenix has crazy hard water ) - pebble tec finish on pool
I've taken the PH down from 8 to 7 twice now with MA and that swing seems to precipitate out a fine red-brown powder. it's most pronounced at the lowest PH levels and as the PH creeps up, the precipitate rate slows down. I brush daily, so there has not been any staining, which I guess is thankful. The DE filter picks it up, and I've backwashed twice to get rid of it.
The Phoenix Water test report shows
Alkalinity 117 - 187 ppm
Iron 0-7 ppb
Sodium 73-194 ppm
TDS 328-774 ppm
Hardness 190-289 ppm
I just did a 90% drain/refill with tap water to lower my CYA to that 55 level ( should have gone to 95% drain I guess ) so the water is almost all 'tap water'. I guess it could be some other thing, but I've had the chlorine drifting down from 20 to it's 8 level over the past week. I haven't detected CC in the past week, and did a .5 OCLT pass before letting the kids in the pool.
I guess the easiest way to check if it's iron would be to use the strongest magnet I have to see how it reacts.
So my question really is : is this normal / OK ?