Borates vs. Borax & Baking Soda use

[Daf-Tekno]

Hi There,

I'm just starting up using borates (to control pH instead of TA).

But if the borate level is basically the amount of Borax in the water, and you also use Borax to raise pH, how do you stay at a desired borate level yet still have the ability to raise pH? (If, say, it's too low for just aeration).

And does Baking Soda effect borate levels?

How do you leave borate levels alone yet increase pH and TA?

Thanks - D

 

[chem geek]

In a pool or spa using a hypochlorite source of chlorine, the pH tends to rise not drop so one doesn't normally use Borax so the borates increasing simply doesn't happen.

Baking soda affects mostly TA and does not affect the borate level at all.

You can increase pH and TA without changing borates by using pH Up washing soda (sodium carbonate aka washing soda) or can change mostly TA and not so much pH and not at all borates by using baking soda (sodium bicarbonate). However, you shouldn't normally need to increase your pH unless you are using a net acidic source of disinfectant or oxidizer.

 

[Daf-Tekno]

Hi Chem Geek,

I'm now resetting my tub to TA 50 / CYA 30 - 40 / CH 100.

I seem to remember the thread on Borate use saying you should wait until pH is 7.4 - 7.6 & TA is 70 - 80 before you should add the Borax / Muriatic acid.
I assume that, me being a Spa and thus operating under slightly modified conditions, instead of waiting until I reach TA 70 - 80, I wait until TA is 50 / pH 7.4 - 7.6 then add the Borate 'mix'..?

I'm starting to assume that all posts here have an invisible asterix relating to a ghost footnote, stating:
"Information for Swimming Pools, NOT NECESSARILY for Spas & Hot Tubs! Check before use in such!".

Hey, it's like being an AppleMac user all over again..! (Or a Pentax DSLR owner in North America...)

Thanks - D

 

[chem geek]

Yes, you get your other parameters set, such as TA to 50 ppm in the spa, before adding the borates. Boric acid is easier to use to increase borates since it won't swing the pH, but if you can't get that in Canada then the borax and acid will work but you need to alternate adding them in partial quantities. I'd start with the acid first, then the Borax, and do this split into at least fourths since that amount of acid will lower the TA by 28 ppm before the borax raises it back up again -- the pH will drop from 7.5 to 6.2 but you'll add Borax right after to get the pH back up.

You should be able to find boric acid at pharmacies in Canada (see this link or this link). For 1700 liters, you need 486 grams to get 50 ppm borates (ppm Boron) so that's just under 4 bottles at $6.49 each so not cheap, but more convenient. I presume the Borax and acid are quite a bit less expensive, but have the pH and TA swing more wildly during the addition of each. This link claims you can buy boric acid in Canada at big box stores, but I believe they've removed those due to toxicity (and cancer) concerns from accidental inhalation or ingestion of concentrated product. You could also try Gesswein Canada which at $9.18 per pound (454 grams) is much more reasonably priced since 1 pound is close enough to what you need.