So I did the borates and it looks GOOD. now about TA for the future

[peril]

Adding borax wasn't bad and ph rebalanced out nicely after the acid.

(Just remember - do as you oughta - add acid to water )

before starting the TA was ballpark correct, about 80-100 ppm. Couple of questions..

1) Does the TA chemistry change once the borates are in play? (I guess that the acid add could reduce TA as it neutralized the sodium bicarb that was eaten up over and above the borax buffer ph adjustment?)
2) how should Alkalinity adjustments be done in conjunction with the borate adjustments in the future?

My thoughts for it being a pain in the a** to get the TA corrected after borate add would be the ph adjustment step of the acid eating up the already too low sodium bicarb in the pool, effectively eliminating it as a potential buffering agent.

Thanks for reading.

 

[duraleigh]

TA is normally the least (and last) important parameter to adjust.

Have you read "The ABC's of Pool Water Chemistry" up in Pool School? It'll give you some guidelines as to your TA level and you will see it is somewhat dependent on your chlorination method.

 

[peril]

I've been doing tf methods / chemical adds for about 2 years, this is my first year to try the borates. As long as there is no trouble maintaining TA in a borate pool with with bicarb all will be well.

Was asking more because of the guidance to "get the TA right BEFORE adding borates".

 

[JasonLion]

Adjusting TA is easier when you don't have borates, but it isn't any different. It just takes more acid to lower PH, and more aeration to raise the PH back up once you have borates in the pool.

 

[chem geek]

You can think of pH adjustment as pushing or pulling on a spring and the borates as increasing the stiffness of that spring. So if you push with the same amount of force (i.e. add the same amount of acid) as without borates, you move the spring less (i.e. the pH changes less). If you want to change the pH more, you need to add more acid. So as Jason wrote, you can accomplish the same things as before with regard to pH movement, but it takes more chemical or aeration to do so. This is why it is usually best to adjust your pH and TA levels before adding borates, but it is not impossible to adjust these after borates have been added and I describe this more below.

As for TA, nothing changes there in that it takes exactly the same amount of acid to lower the TA as before. However, for the TA lowering procedure, it would take more acid to get the pH to the same low 7.0 to 7.2 starting point for the procedure (so the TA drops more in this first step with borates than without). The rate of pH rise would also be slower. So this iterative part of the procedure in some sense may work better in terms of keeping the pH low for longer, but the problem then becomes what happens when you are done with that and want to raise the pH with aeration alone. You now have to wait longer or have more aeration to get the pH back up. Whether this overall procedure is easier or harder with borates may be a matter of opinion, but it's certainly harder to explain since the pH appears more "stuck" when borates are present and having the pH come back up a little during the iterative part of the procedure is one of those indicators that more acid is needed to get the pH back down. With borates, that "indicator" of when to add more acid becomes harder to see.

 

[peril]

Thanks Chem geek - I was remembering my pKa / buffering charts from freshmen chem , like that analogy of the spring, makes it easier to think about how the pool will react to ph adjustements.

It hasn't been a hard time maintaining the ph with the sodium bicarb / (3" tabs) + powder shock, and haven't had to make a ton of adjustments once the pool hit the TA number.

I'm trying to move to the all B's method ( borax / bleach / baking soda / acid) and getting rid of the tabs / shock. (After reading about the cause of algae later in the season, seems like the cya is building up thru the year to a point the chlorine effectiveness is starting to be squeched out.)

Really appreciate the response!

 

[chem geek]

It's mostly bleach and acid that you will use. You usually don't need to use baking soda because normally your TA won't be dropping. You also usually don't need the Borax since your pH will tend to rise, not drop. Of course, you can use Borax with acid or use boric acid directly to increase borates.

And yes, continued use of Trichlor tabs will increase CYA reducing chlorine's effectiveness unless you proportionately raise the FC level to keep the FC/CYA ratio constant. When the active chlorine level drops due to higher CYA at the same FC, algae can grow faster than chlorine can kill it. Using a source of chlorine without CYA lets you prevent this rise. The following are chemical facts independent of concentration of product or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.