# Thread: Pool Calculator Results Question

1. ## Pool Calculator Results Question

Here are my #'s:

FC 3
CC 0
TC 3
PH 7.4
ALK 60
Cal 270
CYA ...maybe 5..ish (trying to get some in there)
Temp 60

If I am using the PC correctly, our pool has a "potential to become corrosive to plaster". Umm, what do I do now?

2. Don't panic. As you add Cyanuric Acid (the pure stuff), the pH will drop so you'll have to add either 20 Mule Team Borax or Arm & Hammer Washing Soda (not the detergent) to raise it at which point the TA will go up and the water will be less corrosive. You can also raise the pH a little to 7.5 or higher and you'll be fine. Finally, as the water warms up, it will be less corrosive. Don't sweat it. If the index were -1.0, then you'd want to fix things more quickly, but since you're doing chemical adjustments now anyway, just add more CYA and keep the pH up and you'll be fine.

Richard

3. Thank you, Richard

You know, we really do appreciate our gurus

4. As a rule of thumb I run my pH higher by 0.1 for every 10 degrees of temprature below 75.

i.e. for water temp of 75F pH is 7.5
for 65F pH is 7.6
for 55F pH is 7.7
for 45F pH is 7.8

This works well for me over the winter as I don't close my pool here in sunny "Kaaliphorniya"

my 2 Cents..

5. It turns out that roughly speaking for every 15F drop in temperature, water will rise in pH by 0.1 so the saturation index doesn't move very much even from 80F to 36F (the pH rises by 0.3 and the index drops by about 0.1). So though you can manually try and adjust the pH, in a pool with very stable pH it will adjust by itself as the temperature changes. This is what happens in my pool every season, though I did notice a larger rise in pH over this winter possibly due to the higher TA I started with and more carbon dioxide outgassing (in spite of the cover being on most of the time).

Richard

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