Lowering CYA: How Long Can I wait to properly balance pool

[EllieWilliams]

"is there a safe period of time that passes before corrosion of plaster likely?"

Preparing pool for winter in Houston TX; this will be the start of BBB, too. CYA was at 160 last week, so emptied 1/2 the pool and brought it down to 80 this last weekend and intend to do another 1/2 to bring down to 40 next week.

Before 1/2 empty:
FC: 20
CC: 0
PH: 7.8
TA: 110
CA: 250
CYA: 160

After 1/2 empty, then refill:
FC: 23 (shocked)
CC: 0
PH: 7.8
TA: 240
CA: 150
CYA: 80

After 1 gallon muriatic acid (two part introduction) (yesterday):
FC: 21
CC: 0
PH: 7.0
TA: 120
CA: 150
CYA: 80

Temps:
Out: 50 low, 75-80 high
In: 70-72

Calcite Saturation Index:
-.7 to -.8

 

[jblizzle]

Re: Lowering CYA: How Long Can I wait to properly balance po

Why did you add so much acid and lower the pH so far?
That is a real problem as the pH test is not valid when the FC > 10ppm ... you should not test pH when the FC is high as it will read a false high level.

What this means as your pH was probably fine and now it is WAY too low, but it is hard to know how low it is since the pH test is not going to be correct until the FC drops below 10ppm.

You should add some borax to raise the pH so that it is reading up around at least 7.8 now (but not way above 8.2) and that should at least get the pH close to OK.

 

[EllieWilliams]

Re: Lowering CYA: How Long Can I wait to properly balance po

I'm sorry, I didn't explain myself well with my original post. I am going to assume that the lack of responses means that my pool will survive my punishment until Friday, when I complete the task at hand. Thank you for your input.

 

[jblizzle]

Re: Lowering CYA: How Long Can I wait to properly balance po

So I guess my warning about the pH was not adamant enough?

 

[EllieWilliams]

Re: Lowering CYA: How Long Can I wait to properly balance po

It was heeded.