YoYo Effect? Total Alkalinity vs pH

[LaROckl]

I searched exhaustively... and apparently, I am to stupid to figure this out.

Free Chlorine... 4.0
CYA... 50
CH... 260
pH... 7.4
TA... 40

I've been using 20 Mule Team Borax to raise TA... then, Muriatic Acid to lower pH... then, 20 Mule Team Borax to raise TA... then, Muriatic Acid to lower pH... etc.

Sodium tetraborate decahydrate is the chemical name for one form of Borax. Borax is also sold in the pool industry in a slightly more concentrated form, sodium tetraborate pentahydrate, for a much higher price. But, once they are dissolved in water, both chemicals are identical.

I seem to be chasing my tail... how does one raise TA and then *not* lower TA when adding Muriatic Acid to adjust pH? I seem to be observing a lineal correlation?

Any observations and/or advise is greatly appreciated!!!!

Thank you

dennis

 

[mknauss]

Raise your TA to 70 ppm. When pH reaches 8+, lower to 7.6. See if the pH stabilizes around 7.8 to 8.

 

[jblizzle]

Borax is not the proper chemical to raise TA. You should be using baking soda which raises TA more than pH. The acid will always lower both pH and TA.

What pH are you trying to maintain? Try to leave it up higher.

 

[LaROckl]

OK, do *not* use Sodium Carbonate to raise TA... *use* Sodium Bi-Carbonate (baking soda) to raise TA.

So, i'll take TA to 70-80 using baking soda (sodium bi-carbonate)... then, bring the pH down and see if the TA holds.

Thank you Marty and Jason!

 

[jblizzle]

I would not even raise the TA that much. Maybe up to 60ppm and then let the pH stay higher.

 

[ckendalls]

As pointed out above use Baking Soda to raise TA. Borax is not what you should use to raise the TA unless you are also trying to raise borate levels... Do you know how many boxes of Borax you have added over time? Your borate levels could be high.

 

[an1vrsy]

Have you tested your fill water? Once you raise TA to 60 or 70 ppm, your fill water may keep TA in that range of 60 to 70 ppm. Then all you’re lowering is pH. So when it gets to 8.0 you’re knocking it back down to 7.6

 

[LaROckl]

I'll try to keep this short...

I stripped the old plaster and re-plastered about 4 months ago (total drain and refill). Borax is what I used the previous 13 years. I have not attempted to adjust the TA since the re-plaster... I tested a couple of weeks after the re-plaster when I obtained my first Taylor 2006 kit. TA was @ 80 on the first test (about 14 weeks ago) and has steadily decreased down to 40 as of this morning. I have not tested the fill water with the Taylor 2006 TA test but I did pH test it and it was @ 8.4 so yes, the fill water is alkaline. I should also add that I *VERY* rarely use the fill water to refill/top-off the pool... I live in New Orleans and there is enough rainfall to keep the pool full.

My guess is that the new plaster is curing/stabilizing somewhat faster than I had imagined it would. I have reduced acid injection from one (1) gallon per week down to 1/2 gallon per week over this period of time.

I tried to keep the original post as free of my past foibles as possible in an effort to reduce confusion... not very successfully.

I will say that thanks to this website... I switched from fresh water to chlorine generator ...and, the pool has been crystal clear the entire time... and yes, TROUBLE FREE!