Any interactions with Boric Acid?

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diamonddog

diamonddog

0
Nov 24, 2012
95
Irvine, CA
Just added some Sodium Bicarbonate to raise TA from 40 to 60. Added muriatic acid the day before to lower pH a tad.

Need to add boric acid to raise it 10 ppm for the pool season. Should I wait to add it or is it ok? This is the pure boric acid and not borax.
 
ajw22 said:
How are you measuring your borates? 10ppm is usually a rounding error in borate measurements.

By the time you read this it will be fine to add boric acid.

Borates in pool - Further Reading

www.troublefreepool.com www.troublefreepool.com
Click to expand...

  1. Collect a sample (44 ml for 4.5 ppm/drop or 25 ml for 7.9 ppm/drop or 50 ml for 4.0 ppm/drop)
  2. Add 5 drops of Taylor R-0009 (sulfuric acid; part of TA test) [EDIT] or whatever is needed to get to a yellow color in the subsequent step [END-EDIT]
  3. Add 5 drops (maybe less) of Bromotyhmol Blue pH indicator dye; sample should turn a yellow color; if not, add more dye until a yellow color is shown
  4. Add Taylor R-0010 drop wise mixing with each drop until the sample just turns a blue color (sodium hydroxide; calcium buffer part of CH test)
  5. Add 1 level spoon (1/8th teaspoon) of Mannitol powder; the sample will turn yellow if boron is present; NOTE: For the 44 and 50 ml sample or when expecting borate levels higher than 50 ppm, use 1/4 teaspoon of Mannitol (see this post for why).
  6. Add Taylor R-0010 drop wise with mixing until the sample just turns blue; record the number of drops in this step
  7. Multiply the number of drops by 4.5 for a 44 ml sample or by 7.9 for a 25 ml sample or by 4.0 for a 50 ml sample to get ppm Boron
 
diamonddog said:
  1. Collect a sample (44 ml for 4.5 ppm/drop or 25 ml for 7.9 ppm/drop or 50 ml for 4.0 ppm/drop)
  2. Add 5 drops of Taylor R-0009 (sulfuric acid; part of TA test) [EDIT] or whatever is needed to get to a yellow color in the subsequent step [END-EDIT]
  3. Add 5 drops (maybe less) of Bromotyhmol Blue pH indicator dye; sample should turn a yellow color; if not, add more dye until a yellow color is shown
  4. Add Taylor R-0010 drop wise mixing with each drop until the sample just turns a blue color (sodium hydroxide; calcium buffer part of CH test)
  5. Add 1 level spoon (1/8th teaspoon) of Mannitol powder; the sample will turn yellow if boron is present; NOTE: For the 44 and 50 ml sample or when expecting borate levels higher than 50 ppm, use 1/4 teaspoon of Mannitol (see this post for why).
  6. Add Taylor R-0010 drop wise with mixing until the sample just turns blue; record the number of drops in this step
  7. Multiply the number of drops by 4.5 for a 44 ml sample or by 7.9 for a 25 ml sample or by 4.0 for a 50 ml sample to get ppm Boron
Click to expand...


OK, so short answer: You are using the Mannitol titration test. Great!

10ppm worth of boric acid will only have a very small effect on pH, decrease of 0.1 or less. Maybe just noticeable when starting in the higher sevens, not noticeable in the lower sevens with a drop test, I'd say.
 
mgtfp said:
OK, so short answer: You are using the Mannitol titration test. Great!

10ppm worth of boric acid will only have a very small effect on pH, decrease of 0.1 or less. Maybe just noticeable when starting in the higher sevens, not noticeable in the lower sevens with a drop test, I'd say.
Click to expand...

Thanks for the reply. I was more concerned with negating the Sodium bicarbonate I added yesterday to bring up my TA.

I know that you should not add muriatic acid and bicarbonate at the same time as it negates it. But was wondering about boric acid and if I have to wait, how long?
 
Adding boric acid will not change TA. You are basically replacing carbonate alkalinity with borate alkalinity, keeping total alkalinity constant.

Similar to adding (dry) CYA: In this case carbonate alkalinity gets replaced with CYA alkalinity, keeping total alkalinity constant.

Carbonate Alkalinity getting too low is really only a concern when chlorinating with Trichlor, in this case you actually want a certain level of CO2 outgassing to actively compensate the ph-drop by Trichlor, and not just buffer the effect.

When chlorinating with liquid chlorine or an SWG, you don't have to worry about that. Just make sure that CSI is in the range where you want it, and that's all that carbonate alkalinity matters for. And that's been considered automatically in PoolMath.

None of the chemicals we use really negate each other. You can for example compensate the small pH change from adding baking soda by adding muriatic acid. But the acid will only compensate a small portion of the TA-change. The two chemicals don't exactly cancel each other out. But there is not often a scenario where adding both at the same time makes sense.

In case of adding boric acid you don't really have to wait long after having added muriatic acid or baking soda. Maybe let the pump run for 30min to make sure they are properly mixed in.

I'd usually add boric acid first and then see if pH needs further adjustment.
 
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