Borates - Why and How

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JasonLion

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Borates - Why and How

Why

Adding borates can improve your experience with your pool, but is completely optional. If you do plan to use borates, wait until everything else is settled down before adding borates, especially TA and PH. The only situations where we specifically recommend using borates are for pools with a negative edge or other very large water feature creating huge amounts of aeration and for spas using the dichlor and then bleach method. All that said, borates have proven popular with a fair number of people.

Pros

  • More stable PH
  • Helps prevent algae
  • Helps prevent scaling in a SWG cell
  • Silky water feel
  • More sparkle
Like baking soda, borates help stabilize the PH. Unlike baking soda, borates do not also put upward pressure on the PH. Larger quantities of an acid or base are required to make a given PH change with borates as compared to without borates. When your PH tends to drift up, borates don't change the amount of acid you need to use, but they do allow you to add acid less often. They also allow you to lower your TA level more than you could otherwise, reducing the upward pressure on PH.

Borates help prevent algae. Borates won't completely prevent algae from growing, but they do slow down algae growth and make it easier to kill off when you do get algae.

The silky feel and added sparkle are subjective. Not everyone notices these benefits. However, most people do appreciate the change.

Cons

  • Additional expense
  • Concerns about risks to pets
  • Not a magical potion to solve all pool woes
In all cases, you should train your pets to not drink from the pool. There are various chemicals in the pool that pose some risk to pets. Dogs that get all of their drinking water from the swimming pool should still not show any symptoms from borates. However, they would be close to the threshold for showing symptoms, rather than 1/100th the level for showing symptoms, as would be required for human safety.


How

We recommend maintaining borates between 30 and 50 ppm. That normally means raising the borate level to around 50 each spring, so that it will still be above 30 come fall.

Before you start on borates, adjust your TA level toward the low end of the appropriate range for your pool type. See the Recommended Levels chart for appropriate levels. It is easier, and better, to adjust TA before adding borates than it will be after.

There are two approaches to adding borates to the pool: boric acid, or a combination of Borax and muriatic acid. Using boric acid is just slightly more expensive, in most cases, and much easier. Borax and muriatic acid takes more effort and handling that much acid is just slightly risky, but saves just a little money (if you shop carefully).

In either case you can use PoolMath to calculate the quantities required.

Boric Acid

Boric acid can be purchased from DudaDiesel and The Chemistry Store. Granular is much easier to work with than powdered. Technical grade is fine.

Boric acid can be distributed across the surface of the pool. Keep the pump running for at least one hour after adding boric acid, and then test the PH and adjust if needed. Boric acid will just slightly lower the PH. Usually the PH change is small enough that no further adjustment is required.

Borax and Muriatic Acid

Borax and muriatic acid can be found at grocery stores and hardware stores respectively. Make sure you double check the strength of the muriatic acid, using half strength acid when you thought it was full strength can lead to problems with PH.

When adding to the pool, you add one gallon of 31.45% muriatic acid, followed by 3 1/2 boxes of Borax, use PoolMath to verify the amount and double check the weight on the box. (For pools smaller than 10,000 gallons it is better to add a half gallon of acid followed by about 1 3/4 boxes of borax each time.) Acid should be poured slowly in front of a return jet with the pump running. Borax can be pre-dissolved in a bucket and then poured slowly in front of a return.

That process is then repeated until you have added the correct total amounts to the pool. The final dose will, of course, be smaller. If you see any undissolved borax, brush the entire pool to help mix it in and get it to dissolve.

24 hours later, test the PH and adjust as needed.

Testing

None of the available borate tests are especially precise. Fortunately, the exact level is not critical and just needs to be in the 30 to 50 ppm range. We recommend using LaMotte Insta-Test Borate Test Strips. They aren't great, but they seem to be the best available choice that isn't wildly expensive.
 
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pooldv

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Thanks for the updated info! Interesting to note the recommendation to add borates to bleach maintained hot tubs. For reasons I cannot fathom I never even considered adding borates to our hot tub even though I have had, and like, borates in the pool for years. Heading off to PoolMath to see what I need for my next weekend project. :)
 

TheDerf74

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May 16, 2013
31
Huntsville, AL
Jason, if you were a first time borates adder like me, which method would you recommend? The boric acid route or the borax and MA route? Both seem very similar in price.
 

johnm

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Jul 9, 2011
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For any living in Houston, Industrial Chemical Co. have boric acid for sale to the public.
I just got quoted $70 for 50Lbs powder or granules.
 
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Tomcat77

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Aug 31, 2013
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San Diego, CA
Just my $.02…..I have four pools that now have borates, and all of the owners love the water. I did the first one with Borax and MA, and quickly decided I wasn't doing that again. I haven't found any shop in or around San Diego where I can get a better delivered price than Duda Diesel for technical/industrial grade boric acid, and the price was nearly identical to doing the borax/muriatic acid, plus eliminating about 80% of the effort. And definitely go granulated.
 
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iam4iam

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May 5, 2012
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Johnson City, TN
Waiting for freight quote from Duda for a bulk order. 55-lb pail is $80 after shipping. Five 55-lb bags are $50 each before shipping, so it'll be interesting to see what the difference is when freight is included. Would last 15+ years. I have room to store it, but is the shelf-life that long?
 

JoyfulNoise

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Waiting for freight quote from Duda for a bulk order. 55-lb pail is $80 after shipping. Five 55-lb bags are $50 each before shipping, so it'll be interesting to see what the difference is when freight is included. Would last 15+ years. I have room to store it, but is the shelf-life that long?
WOW! That's a lot of boric acid.

I would suppose that if you can keep it dry and cool, it will last a while. I like the 55lbs bucket from Duda Diesel as it has a sealed lid that snaps tight and has a moisture ring seal around it. Not sure if you can close up one of their bags as easily.

Other uses for BA include cockroach and ant poison as well as mold remediation on wood structures. Good stuff to have around the house for the occasional DIY projects. You can also mix a small amount of it with Elmers Glue to make a silly putty compound.
 
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iam4iam

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Wow, JoyfulNoise, thanks for the useful info!

On second thought, one perspective I often fail to consider is the annual savings (as oppposed to what I tend to focus on, percent savings. Even if the shipping were free, my total savings for 15+ years worth of acid would be $150. That's a 37.5% savings, and at face value, $150 is a lot, but when looked at from the perspective of $10/year, it seems silly to consider purchasing such a huge amount! I'm about to order the 55-lb bucket.
 

JoyfulNoise

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Wow, JoyfulNoise, thanks for the useful info!

On second thought, one perspective I often fail to consider is the annual savings (as oppposed to what I tend to focus on, percent savings. Even if the shipping were free, my total savings for 15+ years worth of acid would be $150. That's a 37.5% savings, and at face value, $150 is a lot, but when looked at from the perspective of $10/year, it seems silly to consider purchasing such a huge amount! I'm about to order the 55-lb bucket.
My 16,000 gal pool took ~40lbs to get to 50ppm. I used the remaining 15lbs over the course of a season to replenish what was lost through back washing and rain water dilution. I have to order another small quantity at some point later in the season so I have it on hand.

Borates in my pool water has been a net positive for me. Better pH control (let's me run my TA on the low side) and I got a little efficiency boost in sanitizing as the SWG could run a little easier. Not everyone gets positive results so I hope it works out for you (another reason possibly not to buy so much up front).
 

iam4iam

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May 5, 2012
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Johnson City, TN
Thanks. I had borates in my pool last year but I used the borax muriatic acid route. I noticed the same exact advantages that you listed. I haven't been aware of the SWG advantage last year, but I did read about that recently as well.
 

JoyfulNoise

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Thanks. I had borates in my pool last year but I used the borax muriatic acid route. I noticed the same exact advantages that you listed. I haven't been aware of the SWG advantage last year, but I did read about that recently as well.
When I started fooling around with borates, I went straight for the boric acid route because I was paranoid about calcium scaling. I know the muriatic acid/borax method works just fine, but I love the simplicity of the boric acid granules. As well, the BA dissolves very rapidly (at least in my pool it did) and that was nice only having to give a minimal brushing afterwards to promote mixing.

Yeah, I would never tell anyone to do it for the sanitizing benefit as I really can't say with any certainty as to why that is other than just some hand-waving argument that boron has biocidal properties. I'm not sure anyone has ever tried quantify it and there's plenty of folks that report no improvement in sanitation whatsoever.

The pH buffering effects are widely known and quantified in multiple sources (scholarly papers and chemistry textbooks), so that's a benefit a lot of pool owners can count on if the particulars of their pool water chemistry warrant it. I think there's also a cohort of pool owners who see no benefit from the buffering effects as well and so it would be interesting if there existed a definitive collection of data that could help a pool owner predict if adding borates would be useful or not. To my knowledge, there's no predictive model out there, only individual anecdotes.

Sadly the Achilles Heel in all this is the lack of a really good titration based test for borates. Hanna Instruments sells a test solution but it's really expensive and it's upper test limit is only a few ppm's. The LaMotta InstaTest strips are ok, but I find them to be way too course. There was a Canadian company selling a test kit but they're not in business anymore. Luckily getting borate concentrations exact to the single-digit ppm's is not necessary...
 
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iam4iam

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May 5, 2012
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Johnson City, TN
Agreed. All I know is my borates last year were probably around 40 ppm and with a TA of 70 my pH never budged, my water stayed crystal clear, and my SWG still looks new. I'm going to have to have to add equal amount this year as I did last year since we just changed our liner and I'm starting from zero, but in the future I shouldn't have to add as much so for the relatively small cost I'll take the benefits whether anecdotal or empirical
 
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chem geek

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Yeah, I would never tell anyone to do it for the sanitizing benefit as I really can't say with any certainty as to why that is other than just some hand-waving argument that boron has biocidal properties. I'm not sure anyone has ever tried quantify it and there's plenty of folks that report no improvement in sanitation whatsoever.
Regarding Borates and algae, see Table 18 in this link and its associated scientific references. It's not a strong algaecide, but at 50 ppm it does slow down algae growth. It would probably be most effective above 100 ppm but as noted in Are Borates Safe to Use?, the EPA limits boron concentration to 50 ppm in swimming pools.

The pH buffering effects are widely known and quantified in multiple sources (scholarly papers and chemistry textbooks), so that's a benefit a lot of pool owners can count on if the particulars of their pool water chemistry warrant it. I think there's also a cohort of pool owners who see no benefit from the buffering effects as well and so it would be interesting if there existed a definitive collection of data that could help a pool owner predict if adding borates would be useful or not. To my knowledge, there's no predictive model out there, only individual anecdotes.
The pH buffering effect is well known and documented (see pH Buffer Capacity for relative buffering strength of borates, carbonates, and CYA), but people incorrectly believe that the borates will lower the amount of acid that needs to be added. The borates add pH buffering without adding carbonates so they let one go longer between acid additions, but the total amount of acid over time is the same unless one also lowers the TA level since it is TA (specifically the carbonates portion of TA) that results in rising pH from carbon dioxide outgassing.

Sadly the Achilles Heel in all this is the lack of a really good titration based test for borates. Hanna Instruments sells a test solution but it's really expensive and it's upper test limit is only a few ppm's. The LaMotta InstaTest strips are ok, but I find them to be way too course. There was a Canadian company selling a test kit but they're not in business anymore. Luckily getting borate concentrations exact to the single-digit ppm's is not necessary...
There is an expensive Taylor K-1541 drop-based test kit that would require diluting the water sample to get into its high range of 5-15 ppm. However, one can make their own drop-based titration test based on what Apollo Pools in Canada used to sell (they are no longer in business) by buying mannitol and bromothymol blue at the links in this post and following the instructions in the post that follows that also uses Taylor reagents R-0009 (sulfuric acid for the TA test) and R-0010 (calcium buffer for the CH test).
 

JoyfulNoise

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@chem geek,

Awesome! Thank you so much for those links on boron's biocidal activity. I am bookmarking them for future reference and I will read them carefully. And thanks for the boron titration test recipe as I may try it out someday to see if I can make it work. The kids love seeing me do pool water testing (and soil testing too for gardening). I let my oldest help out with putting reagent drops in as it's a great way to introduce them to the fun parts of science.
 
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