OMG, what have I done?

[YippeeSkippy]

I've been pool and spa stored, I tell ya!

Emptied, cleaned and refilled my hot tub. Added a little too much Diclor so to neutralize a bit of the chlorine I added hydrogen peroxide 3%. Worked like a charm. Who knew??

Went to local pool and spa store to get a new filter and realized I hadn't used the Robards pH stabilizer product I normally use on start up (can't recall the exact name but you add a bottle of this on start up to qwell pH drift). The salesman said that since the tub is already hot those products don't work so well when added to hot water, and instead to use an entire 16 oz bottle of Brilliance brand Total Alkalinity Increaser.
Well, I don't know what this is about but now I have pH out the roof and with repeated administration of Muriactic Acid my TA is finally down to 100 and my pH is still 8.2 or greater. Currently my FC is 8 with CC of .5.

HELP!?

 

[Melt In The Sun]

Keep adding acid til you get it down!

 

[chem geek]

The salesman said that since the tub is already hot those products don't work so well when added to hot water, and instead to use an entire 16 oz bottle of Brilliance brand Total Alkalinity Increaser.

He had you increase your TA and a higher TA causes the pH to rise more quickly. Unless your TA was very low (below 50 ppm), you didn't need to increase it. Acid and aeration in combination will lower the TA (or acid addition over time by itself since carbon dioxide outgassing still occurs without aeration, just more slowly).

 

[YippeeSkippy]

The salesman said that since the tub is already hot those products don't work so well when added to hot water, and instead to use an entire 16 oz bottle of Brilliance brand Total Alkalinity Increaser.

He had you increase your TA and a higher TA causes the pH to rise more quickly. Unless your TA was very low (below 50 ppm), you didn't need to increase it. Acid and aeration in combination will lower the TA (or acid addition over time by itself since carbon dioxide outgassing still occurs without aeration, just more slowly).

How is adding the Alkalinity Increaser anything like the Robards product though? I thought the point was to minimize pH drift, not take it out of the atmosphere high, LOL. I've learned my lesson-either remember the Robards product at the git go or go without!

After many additions of MA, the pH is now about 7.4. I keep rechecking in fear of it bottoming out now in some bizzarro twist.

 

[chem geek]

It's Robarb, not Robard. I don't see a product called "pH Stabilizer". There is Robarb Perfect pH which from this list of MSDS sheets for Robarb products is a phosphate buffer. Is that what you normally use? A phosphate buffer will lock the pH a lot, but it will also precipitate calcium so doesn't work well for hard water.

Anyway, your using Alkalinity Up instead increased the TA and that makes the pH rise more quickly even though there is more pH buffering. This is because TA is BOTH a pH buffer AND a source of rising pH in its own right. The Robarbs product is a pH buffer that does not move pH on its own (i.e. there is no extra carbon dioxide outgassing from it). So in the future, either use the Robarbs product or if you don't use it, then get your TA down to 50 ppm or so and possibly use 50 ppm Borates as an alternative pH buffer.