What does the Borax do and does it affect the PH or Alkalinity
What does the Borax do and does it affect the PH or Alkalinity
Borax is used to raise pH with minimal effect on alk as opposed to soda ash which raises both.
Borax used in this manner along with muriatic acid to keep the pH balanced is a secondary pH buffer and algaestat. IMHO, it is a very useful additive and almost a necessisity with a SWCG but beneficial to any pool! It has mimimal impact on TA but really helps stabilize the pH around 7.6 to 7.7 for longer periods of time than without.
It also will deter algae for much longer than without. (I go on vacation every summer--we are talking about July in Florida--and I just shut off the pool for two week and when I come back it might be just a tad cloudy but it is NOT green. I just shock it before I leave and maintain 50 ppm borates. If I did not have the borates in the water my pool would be green in a week or less!)
There are other benefits to borates but the are subjective (water 'feels better", it sparkles more, etc.) These effects are reported over and over again and possibly have to do with how the borates affect surface tension.
Retired pool store and commercial pool maintenance guy.
When adding a large amount of borax / muriatic acid (or any chemical), is there a rule of thumb for how quickly to add them?
Are you asking how fast to pour something in or how much to space apart additions of different chemicals?
I can tell you that it is never a good idea to add large doses of anything at one time. Better to dose gradually and sneak up on a target than risk overshooting it.
I would split up the doses and since you've got gallons of acid you could add one gallon of acid and then 100/6 = 16-2/3 pounds of Borax, then acid again, etc. If you add slowly over a return flow in the deep end, then I would wait 5 minutes between additions which should give a reasonable amount of mixing assuming you've got some decent circulation. Put the pump on high if it's a multi/variable speed pump. Also, be sure to lightly brush the side and bottom after doing each addition to ensure thorough mixing. From the quantities you've given, it sounds like you've got a pool around 27,500 gallons or so, is that right?
I'm figuring 27,000 gallons to be safe on the low end. From the math that I've done, the pool should be 32,000 gallons. However, when I add chemicals, they seem to have a "larger" effect than expected so I did some calculations based on the last batch of bleach that I added to the pool and it calculated out to 27,000 gallons. I added 364oz of bleach and overnight my FC when from 1.5ppm to 8ppm. I plan to do the same calculations on the borax addition to see if the effect is equivalent to 27,000 gallons as well. By the way, how do you test for borates?
I would allow at LEAST two hours between doses (with the pump running) to give the chems a chance to properly mix in the pool, then retest before you add more.....
Janet
When adding borax and acid for a secondary buffer and algaestat I usually split it into tow or three equal doses. You really don't have to wait after each addition (I add borax first and then acid) but I do brush down the sides of the pool to "stir" everything after each borax/acid addition. Of course, I do this with the pump running. Let it circulate for about 24-48 hours before readjusting pH or testing your borate levels. It's really pretty much a no brainer if you have calculated the proper amount of borax and acid. If you overdose by a bit it's not a problem at all but generally you want to shoot for 50 ppm for a chlorine or bromine sanitized pool or spa. With biguanide up to 80 ppm will give better protection against pink slime and white water mold.
Retired pool store and commercial pool maintenance guy.
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