High CYA

[Hawk]

I have what I believe to be extremely high CYA. I tested using a Taylor (#2006) FAS-DPD kit. Reading was off the scale. I then mix one part pool water to to one part tap and retested. Still off the scale. I then decided to mix one part pool water to FOUR parts tap water and retested. I now get a reading of approximately 42. My question(s) are, should I multiply the 42 by 4 to get a total of 168 or am I multiplying 42 by 5 for a reading of 210? I know in either case that I will be dumping pool water this afternoon and refilling to get this under control. My thought is start with half the pool water. Does that sound too extreme? I really don't want to pull too much out only to have to replenish.
Thanks.

 

[Isaac-1]

If you have a high water table you need to be careful draining more than a foot or so of water from your pool at a time, or else you take the chance of the pool floating out of the ground.

Ike

 

[duraleigh]

I'm with Isaac-1. If you live on a desert mountaintop, 50% is fine....living at the low end of a swamp requires more caution.

Truth be told, 50% is likely fine but the consequences of misjudging are severe. I would suggest 1/3 at a time.

 

[Hawk]

No high water table here. I'm actually on a view lot above other houses, but can do 1/3 at a time to be safe. I recall the last time it was acid washed they drained it.