Borates in pool - Further Reading

Why should one use Borates

Adding borates to your pool can improve your experience with your pool, but is completely optional.

The key benefit of adding borates to your pool is to help slow pH increase. 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 many pool owners.

Benefits of using Borates

  • More stable pH due to slowing pH increase
  • Helps prevent scaling in a SWG cell
  • Silky water feel
  • More water sparkle

Downfalls of Borates

  • Additional expense
  • Concerns about risks to pets
  • Not a magical potion to solve all pool woes

How do Borates Affect a SWG?

Borates can act as a mild algaecide and so people usually see that “boost” in efficiency because borates can make it harder for algae to replicate. Borates also strongly buffer against high pH changes inside the cell as the pKa is around 9.0 for the boric acid/borate ion buffer system. Keeping the pH in check means that calcium scaling is less likely and thus the cell can run without getting coated with scale. Scale reduces the efficiency of the cell.[1]

How to add Borates to your Pool

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.

How to Add Borates Using Boric Acid

Calculate, using PoolMath, how much Boric acid you will need for 50 ppm.

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

Distribute the boric acid 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 lower the pH slightly. Usually the pH change is small enough that no further adjustment is required.

Do Not Use Roach and Ant Killer for Boric Acid

Roach and Ant killer can contain boric acid and labels may say it is 99% boric acid and 1% inert. However, they will be very fine powders meant for dusting entryways and such. These types of insecticides will also contain anti-caking agents so that they are free flowing as well as many containing diatomaceous earth (DE) to act as an abrasive which removes the waxy coating from the insect's exoskeleton. Without the waxy coating, the insect dessicates from water loss.[2]

DE (uncalcined) and some anti-caking agents are not considered hazardous (in fact, uncalcined DE is a food additive), and therefore are not reportable in the MSDS. That is why they can say it's 100% boric acid powder even though it might be 60% boric acid and 40% other inert ingredients.

Also the insecticide can have a blue dye added to it so you can see where you’ve sprayed it as a bug killer.[3]

How to Add Borates Using Borax and Muriatic Acid

Borax can be found at grocery stores and muriatic acid at hardware stores. Make sure you check the strength of the muriatic acid, using half strength acid when you thought it was full strength 31.45% can lead to problems with pH.

Calculate, using PoolMath, how much Borax and Muriatic Acid you will need for 50 ppm. Verify the amounts using PoolMath after purchase and double check the weights on the Borax boxes and strength of the Muriatic acid. (Is there only one size Borax box?)

The process for adding the Borax and Muriatic Acid is:

  • pre-dissolve 3 1/2 boxes (Do we want to specify box or weight?) of Borax in a bucket
  • pour one gallon of 31.45% muriatic acid slowly in front of a return jet with the pump running
  • pour the dissolved Borax in the bucket slowly into the pool
  • brush the entire pool if you see any undissolved Borax to mix it in and get it dissolved.
  • For pools smaller than 10,000 gallons it is better to add a half gallon of 31.45% muriatic acid followed by about 1 3/4 boxes of Borax each time.

Repeat the process (at what interval?) until you have added the correct total amounts to the pool. The final dose will, of course, be smaller.

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

How to Test for Borates in Pool Water

The exact level of borates 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, and not very precise, but they seem to be the best available choice that isn't expensive.

A mannitol test for borates has been developed by some creative members. It is a bit complex and you can read about it here.

A commercial Borate Alkalinity Test Kit is available. This kit is similar to the TFP mannitol test process but keep in mind that the manufacturer has designed their test around industrial/consumer water sources that DO NOT contain a strong oxidizer like chlorine. So you may have problems with their test method if you don’t first neutralize the chlorine in your sample water.[4]

Borates and Health Concerns

Borates have in the past had a reputation for being unsafe for both humans and pets, mostly dogs. While very high levels can pose some risks TFP Suggested Levels are safe for both. A 100 pound dog would need to drink 8 liters (over 8 quarts) of 50 ppm borate pool water every day just to be at the No Observed Adverse Effect Limit (NOAEL). The level seen for first symptoms is 3 times higher than this amount. And this is literally drinking every day since borates are excreted from the body and do not accumulate so the daily intake level where problems would occur is that which is higher than the rate at which the body flushes out borates.

Boron is an essential nutrient so the body takes in what it needs and excretes the rest, though this process has its limits which is why almost anything is toxic if given in high enough doses. This excretion process is fairly efficient for mammals that use urine primarily to excrete excess nitrogen as urea, but for insects they excrete solid uric acid so do not excrete boron efficiently which is why boron is far more toxic to them.[5]

Are Borates an Algaecide?

While Borates tend to have a minimal effect as an algaecide one shouldn’t utilize them to prevent algae. The boron concentration that that is required to noticeably reduce the risk of algae[6] is far higher than what is generally considered safe so we generally don’t utilize them to prevent algae, we only focus on the benefits for buffering pH changes.

What are the algaestatic properties of borates

The algaestatic properties of borates is over-stated at 50ppm. Borates act more as an "inhibitor" than biocidal agent. In other words, the presence of boron in the water at 50ppm interferes with certain cellular processes going on inside the algae (likely inhibiting key enzymes that contain diol organic structures). By causing this interference, the algae is either slowed in it's replication or it's reproduction is stopped.[7]

Borates only become truly algaestatic at concentrations above 100ppm (and really closer to 200ppm) which would make the water unhealthy to swim in for large mammals and humans. Above 100ppm, there could be chronic toxic effects on very small children (babies) and pets (dogs or cats) that might accidentally (or intentionally) ingest pool water.

Is Borax and Baking Soda the same thing

Borax and Baking Soda are two different chemicals. Borax will increase the pH of the water without increasing the total alkalinty. Baking soda on the other hand will help increase your total alkalinty.