Borax

[roytyson]

I cant find a chart to referance on how much borax to add to raise ph.

Is there such a thing??

I have a 5400 gal easy-set pool.

Thanks

[ohpoolboy]

Check out the sticky at the top of this section ("Using the Bleach Calculator "). Download the Bleach Calculator. It has several other calculations including Borax for pH. :)

[chem geek]

I'm still working on the full exact formulas, but roughly 1 pound (16 ounces) of Borax (Sodium Borate Decahydrate) is an equivalent base to 3.4 ounces of Caustic Soda or Lye (Sodium Hydroxide) which is equivalent to 4.4 ounces of Soda Ash (Sodium Carbonate). As for how much to add to raise the pH by a specific amount, this depends on your TA and starting pH. My calculations show that 1 pound of Borax [EDIT] in a 16,000 gallon pool [END-EDIT] will raise the pH by 0.1 at a TA of 80 and pH of 7.2 but the following chart shows more details. Please use smaller amounts and retest since I could be wrong about this! And let us know your results.


One Pound (16 oz.) of Borax will raise the pH by:
(CYA is 30 ppm; doesn't change a whole lot with different CYA)
NOTE: This is for a pool of 16,000 gallons. Adjust your amount proportionately!

TA Start pH Increase in pH

80 7.0 0.07
80 7.2 0.10
80 7.4 0.15
80 7.6 0.21

120 7.0 0.05
120 7.2 0.07
120 7.4 0.10
120 7.6 0.14

I hope this helps. Please be sure to let me know if this was right! [EDIT] Your 5400 gallon pool would use about one-third of a pound (about 5 ounces) to produce the same pH rise as shown in the above table for my 16,000 gallon pool. Alternatively, in your 5400 gallon pool, one pound of Borax would increase the pH by 3 times the amount shown in the above table.[END-EDIT]

Richard

[chem geek]

Check out the sticky at the top of this section ("Using the Bleach Calculator "). Download the Bleach Calculator. It has several other calculations including Borax for pH. :)
I thought that the Bleach Calculator only calculated how much Borax to use to raise the borate concentration to a certain amount, mostly to use to prevent algae. The last time I looked, the calculator did not figure out how much to add to change the pH by a certain amount nor the other way around.

Richard

[Rangeball]

I thought that the Bleach Calculator only calculated how much Borax to use to raise the borate concentration to a certain amount, mostly to use to prevent algae. The last time I looked, the calculator did not figure out how much to add to change the pH by a certain amount nor the other way around.

Richard


Having just looked at it for this specific reason a few days ago, I believe this to be correct.

Richard, is your chart at all dependent on # of gallons the 1lb is added to?

[chem geek]

Having just looked at it for this specific reason a few days ago, I believe this to be correct.

Richard, is your chart at all dependent on # of gallons the 1lb is added to?
Holy mackerel! Yes, I ran this on my spreadsheet at 16,000 gallons so you definitely need to adjust for that! Good catch!

So if your pool is larger, then increase the amount of Borax you need to add by that relative amount compared to 16,000 and likewise reduce the amount of Borax if it is smaller. Sorry about that! I'll update my post to reflect this.

Specifically, the 5400 gallon pool roytyson is using would use about 1/3rd the amount based on the table.

Richard

[Rangeball]

My 21,200 gallon pool is basically 33% more water than the 16,000 gallon you based the chart on, so I need 1.33 pounds to do the same job as 1# in your chart above.

So a 4# box of borax should give me about a 1.5-2.1 bump in ph, right?

[chem geek]

My 21,200 gallon pool is basically 33% more water than the 16,000 gallon you based the chart on, so I need 1.33 pounds to do the same job as 1# in your chart above.

So a 4# box of borax should give me about a 1.5-2.1 bump in ph, right?
Not quite. 4/1.33 = 3 so the pH jump for 4 pounds of Borax in a 21,200 gallon pool would be 3 times that shown in the table or roughly 0.15 to 0.63 depending on TA and starting pH.

[ohpoolboy]

I thought that the Bleach Calculator only calculated how much Borax to use to raise the borate concentration to a certain amount, mostly to use to prevent algae. The last time I looked, the calculator did not figure out how much to add to change the pH by a certain amount nor the other way around.

Richard

You are right. I was trying to remember the pH module without actually launching the program. The module will show you how much Sodium Carbonbate (Soda Ash) to add in order to raise the pH 0.2 ppm. I thought it showed how much Borax. Sorry for the confusion.:o

[abessellieu]

To Chem Geek: And let us know your results.

I am new at all this, and recently lowered my pH too much (to 7.2) and my plasterer recommended I keep it as close to 7.4 as possible. Since my TA was already 120, I wanted to raise my pH slightly w/o affecting TA, so I used your table to calculate how much Borax to use.

I have a newly (5 days ago) replastered pool that holds about 35,000 gal. By my calculations that is 2.19x larger than the 16,000 gal base you used.

According to your table 1 lb Borax with TA of 120 and pH of 7.2 will give a rise in pH of .07.

So I calculated 4 lb Borax would give me a 1.3 bump up in ph:

4/2.19 = 1.83 x .07 = 1.3

So I added 4 lb Borax at about 10 pm last night and at 8 am this morning my pH was 7.4. This was a little more than I expected, but I thought it might be due to the curing plaster. Doesn't it cause an upward creep in pH?

If this is the case it looks like your table is pretty accurate, but please let me know if you see any errors in my calculations or my logic.

I am still struggling with all of this, but each step I take seems to clear the fog a bit more. I really appreciate your taking the time with the tables and all, because at least it gives me a starting point. Otherwise I'd be totally clueless instead of mildly confused. :o

[chem geek]

Your calculations were correct.

Well, unless you are using an accurate pH meter, the colorimetric pH test is only accurate to within perhaps 0.1 if you're really good so I would say that you were in the ballpark. And yes, during the curing of plaster (gunite, cement, concrete, etc.) the plaster essentially absorbs water and releases calcium hydroxide ( Ca(OH)2 ) which is quite alkaline (basic) and causes the pH and CH to rise. Also, at your TA of 120 and pH of 7.2 your pool water had a somewhat strong tendency to outgas carbon dioxide (relative rate 24.6 where 15 is when many complain of pH rising) which would also cause your pH to rise. So between both factors, it's not surprising that your pH would rise even if you had not added any Borax at all.

[EDIT] One more factor to consider is that in the table you will notice that as you go higher in pH, the rise in pH due to 1 pound of Borax becomes greater. so instead of a .07 pH move you would start to get a .08 and then .09 pH move which when multiplied by your 1.3 factor becomes .10 to .12 instead of .09 though I believe the abovementioned pH rise factors are the more likely cause for the small discrepency. To really test the table, you'd have to have more significant pH moves in which case you should use the midpoint value from the table in the middle range between your starting and ending pH values. [END-EDIT]

Of course, if you or anyone else finds that my tables "seem wrong", please let us know. At this point, it seems that they may be correct.

Thanks,
Richard