The Summer of Shortage
Let’s face it, this summer has been a hot one. For pool owners, the ability to seek relief via a cool plunge just steps away from the backdoor has been needed, now more than ever. Having the supplies needed to keep the backyard oasis crystal clear and inviting, however, has been a real challenge. Just prior to summer, the newswire was abuzz with stories of chlorine shortages. This initially was singled out to only one form of pool chlorine, tri-chlor tablets. The reason for the shortage was a fire and the complete destruction of the manufacturing facility of a company that supplied 40 percent of the US market. This left a big gap in one of the most popular methods for chlorinating pools. We still, however, had cal-hypo tablets and granular and the old reliable liquid chlorine bleach.

The increased demand on the alternate forms of chlorine, coupled with the enormous increase in new pools as well as high demand is causing a domino effect: both cal-hypo and liquid are now very precious commodities for homeowners and professional pool service providers. As a result, many are seeking to find ways to make chlorine go further in the pool. Many of these alternatives involve the installation of costly secondary devices, such as ozone and UV systems. Some are resorting to the installation of saltwater generators that produce chlorine on site and deliver it into the pool. All of these methods have a benefit; it comes, however, at a high additional price and increased maintenance cost. For those looking for a way to improve the longevity and effectiveness of chlorine in the pool, without the addition of a costly device, the answer may be as simple as adding borates to the water.

What are borates?
Elementally speaking, borates are what are known as isotopes of boron. If you geek out on science or are going to audition for the game show Jeopardy, then you already know that boron is number five on the Periodic Table of Elements. Not to be confused with The Fifth Element (which was a cool sci-fi flick), boron was discovered in 1808 by two French chemists. Boron is wide- spread in small amounts throughout the Earth’s crust. It is naturally present in the earth as borate and is found in soil, rocks and water. Due to either underground hot springs or ancient volcanic activity, a lot of it ended up in the California area known as Death Valley. By 1881, the mother lode was located and the Borax Company was born. Since the area was very desolate and over 165 miles from any railway, tons of borate was hauled in wagons, pulled by a team of 20 mules. It was determined that 20 mules could haul a wagon containing 40 tons of borate. Later the mule wagons became the symbol for what is known today as 20 Mule Borax laundry treatment.

What do borates do?
Borates are used in many industries. These are just a few of the beneficial uses:

• Agriculture as a safe pesticide
• As a corrosion inhibitor in cooling systems and auto anti-freeze
• Provides glass and textile strength for cell phone and laptop screens
• Used in eye drops to provide artificial tears
• A fire retardant for clothing
• An anti-fungal and preservative for wood
• Enhances the cleaning ability of detergents
• Considered an essential nutrient for human health

Benefits of borates in swimming pools

• Softens water
• Reduces scaling
• Improves water clarity
• Reduces corrosion of plaster and surfaces
• Improves oxidative power and longevity of chlorine (makes chlorine last longer)
• Acts as a buffer to prevent excessive pH increase
• Helps provide algae control
• Improves swimmer comfort-eyes and skin

At levels in swimming pools of 50 ppm, borates are a safe and effective additive for the overall chemistry of the pool. Pool owners and pool service techs have F. M. ‘Borax’ Smith to thank for the discovery and mining operations in Boron, California, which is one of the largest natural mineral deposits in the world. In pools, borates have a toxicity level similar to common table salt. Normal levels of borates in pools not exceeding 50 ppm are low in toxicity. It would take an average person to ingest several gallons (at once) of pool water for any toxicity to occur. The same applies for animals. The likelihood of either a human or animal ingesting that much in a single instance are virtually nil.

How borates work in pool water
The primary role of borate in pool water is to act as a buffer. Any wise pool pro knows that when it comes to managing water, it is all about balance. pH plays a vital role in the proper production of the killing agent of chlorine known as hypochlorous acid (HOCl). Keeping pH in the level of 7.4-7.5 is one of the keys to ensuring good chlorination. A balanced pH also is vital to prevent corrosion, scale formation and metal staining. Total alkalinity and cyanuric acid (CYA) are both buffers that help to keep pH from drifting downward. Borates are efficient at keeping the pH from drifting up. Borates also act as a good water clarifier, especially in hard water areas. The unique buffering capacity of borates gives them the ability to lock up calcium in much the same way as a metal chelate or sequestering agent would. This action prevents the calcium from combining with carbon and precipitating out as scale. Because the calcium is held in solution, the water has a softer feel and is gentler on the skin. Your pool customers will notice.

Borates act as an anode inhibitor in the presence of oxygen. This means they are excellent at preventing corrosion of less noble metals such as copper. Borates in chlorine generator pools can help to prevent the metal staining that can be a result of galvanic corrosion. So ladders, light rings and heat exchangers are less likely to corrode and will last longer.

Because of the unique ability as a buffer and softener, borates increase the performance and longevity of chlorine in the pool. Many pool techs report longer lasting free chlorine residuals with borates. It is this ability, along with the algaestatic characteristics, that make borates a great algae prevention tool. It should be noted that borates are NOT an algaecide and should not be used directly to kill visible algae in a pool. Borates are strictly a preventative along with good pool maintenance.

Types of borates for pools
As pointed out there are several differing forms of borates. This
is dependent upon what the borate is blended with. Borates are more commonly known as Borax, which is sodium borate. There are a few different forms, which are all simply a combination of boron (remember number five on the Table of Elements), oxygen and sodium. In the pool market, the types of borate products available are:

• Boric acid
• Borax
• Sodium tetraborate pentahydrate

Boric acid. This is a weak acid of boron which when dosed at 50 ppm has very little effect on pH. This has a cost savings in that muriatic acid does not need to be added. It takes 35.06 pounds of boric acid to get a 50 ppm increase in 15,000 gallons.

Borax. This is the same product that is sold as 20 Mule Team Borax in stores. Sodium borate is a powder that is alkaline with a pH of 9.2 and does need the addition of muriatic acid. It takes 54.06 pounds of Borax in 15,000 gallons to get 50 ppm. That is about 11 and a half boxes of Borax from the store. It would take 3.79 gallons of muriatic acid to adjust the pH after treatment.

Sodium tetraborate pentahydrate. This is similar to Borax, however, less is needed as it contains only half the water molecules. It also has a pH of 9.2 so additional muriatic acid is needed after treatment. It takes 42.1 lbs. of sodium tetraborate pentahydrate to provide 50 ppm in 15,000 gallons. It takes 3.29 gallons of muriatic acid to adjust pH after treatment.

More information
There are several options available when it comes to adding borates, and much additional information on borates is available. There are several technical bulletins on borates and the dosing of borates on the Pool Chemistry Training Institute web site, Also, the Borax website ( is interesting in explaining history and uses of borates. As in many situations, sometimes the simplest of solutions is best. This summer continues to be challenging from the standpoint of obtaining the chlorine we need to keep our pools safe and clear. Borates could very well be that simple solution to stretching out the chlorine we need.

About the author
Terry Arko has more than 40 years of experience in the recreational water industry, working in service, repair, retail sales, chemical manufacturing, technical service, commercial sales and product development. He has written over 100 published articles on water chemistry and has been an instructor of technical courses for over 25 years. Arko is a voting member on the board of the Recreational Water Quality Committee (RWQC) and serves as a board member for the California Pool and Spa Association (CPSA). He is also a Certified Pool Operator instructor with the Pool Hot Tub Alliance (PHTA). Arko is currently working as Technical Content and Product Training Manager for HASA Pool, makers of HASA Sani-Clor. He can be reached at



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