Raising pH and Alkalinity

[TRHOD12]

Test results
Cl= 5 oto test
pH=7.2
alk= 90
cya= n/a
ca=didn't test, vinyl liner
water temp= 72f

21,000 gal pool

Opened pool 2 weeks ago, I shocked w/ 6% bleach until help shock level over nite. I added 4lbs of cyanuric acid (cya level was 0). Currently, I am waiting to test cya level again to make sure it has all dissolved.

I was wanting to raise my pH and alk levels alittle. My alk dropped slightly from last year from 120 to 90. My pH normally runs about 7.6. The kids were swimming, and said the pool water burned their eyes alittle.

I can't remember, but it seems like I can add 1 product and raise both pH and alk at the same time, was it baking soda that will do that?? I would like to shoot for a pH of 7.6 and alk level of 100-120

Thanks for your help.

Blessings,

[madwil]

Yes, baking soda will increase both alk and pH...
use PoolCalculator to determine the correct dose for your pool... lost the link but I'm sure you can find it on Google

[CarlD]

I would not follow those steps.

Actually, Baking Soda will raise your T/A more than your pH. It's generally not for raising pH.

The correct chemical to raise both is Washing Soda. Arm&Hammer makes it and it comes in a yellow box in the laundry section.

Baking Soda is Sodium Bicarbonate. Washing Soda is Sodium Carbonate, a different chemical.

However, if your raise your pH with Borax, you will see your T/A rise as well. That's because the measurable level of T/A changes with pH.

So, before you go gung-ho to raise what's already an acceptable T/A level, first use Borax to adjust your pH to about 7.6, then check your T/A again. You may find it's now over 100, and if it is, there's NO reason to raise it.

Carl

[TRHOD12]

Thanks for the pearls of wisdom. I've had the pool almost 6years, and have never had to adjust pH or alk. I'm pretty fortunate.
I'll adjust the pH with the borax only.

I was thinking that since my alk had slightly dropped, that could be contributing to the pH drop also.

Thanks again,

Blessings,

[CarlD]

While T/A and pH are connected, the cause and effect isn't that obvious. A lower T/A won't cause your pH to drop. My pH is good and my last T/A reading was ...40! T/A's main function is to keep pH from fluctuating. If it's not fluctuating, it's not a problem. Some of our SWCG experts tell us that the for an SWCG, the T/A is BEST kept low--between 60 and 80.

When you raise your pH with Borax or Washing Soda, you'll see your T/A increase as well.

No need to make it complicated.

Carl

[chem geek]

The simplest way to think about it is that TA does TWO things: 1) it buffers pH which means a higher TA tends to resist changes in pH from EXTERNAL SOURCES such as acid addition or bleach addition and 2) TA is a SOURCE of rising pH in its own right due to increased carbon dioxide outgassing (i.e. pools are over-carbonated and the TA tells you by how much). These two factors compete with each other with the second being dominant at higher TA. So this means that a higher TA level will cause the pH to rise in a pool, assuming you aren't adding acid in any way, including use of Trichlor pucks or Dichlor powder. Every pool has a "sweet spot" TA level that is low enough to not notice a pH rise. This TA level varies by pool because the rate of pH rise is accelerated by increased aeration of the water so pools with waterfalls, fountains, spill-overs, vanishing edges, etc. tend to need a lower TA level to get reasonable pH stability. The same is true for saltwater chlorine generator pools, partly due to hydrogen gas bubbles increasing aeration.