PEP Tech

Need to Stretch Your Chlorine this Summer? Try Adding Borates

The Summer of Shortage
Let’s face it, this past summer was really tough. Now in the off-season there is some time to contemplate and plan for the 2022 season. One of the big questions service techs are asking is will there be enough product next summer. Despite the challenges many service techs were able to shift and adjust how they maintain their pools. Many alternatives to tri-chlor, liquid chlorine and cal-hypo have become more the norm. Stretching chlorine and getting more performance out of less has become a real art. One of the most prevalent ways to maintain good water quality and make chlorine go further has been adding borates to the water.
What Are Borates?
Borates come from the element of boron. The majority of it comes from California, mined in the Death Valley area. The primary use of what is known as borax was as a laundry treatment for softening water and improving the cleaning ability of detergents.
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. Normal levels of borates in pools not exceeding 50 ppm are low in toxicity.

How Borates Work in Pool Water
The primary role of borate in pool water is to act as a buffer. Total alkalinity and cyanuric acid CYA are also 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.
Because of their unique ability as a buffer and softener, borates increase the performance and longevity of chlorine in the pool.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.
Types of Borates for Pools
In the pool market the types of borate products available are:

  • Boric acid
  • Borax
  • Sodium Tetraborate Pentahydrate

Boric Acid
It takes 35.06 pounds of boric acid to get a 50 ppm increase in 15,000 gallons. There is no need to add muriatic acid.
Borax
Sodium borate is a powder that is alkaline with a pH of 9.2. It takes 54.06 pounds of Borax in 15,000 gallons to get 50 ppm. That is about 11 and a half boxes of 20 Mule Team Borax from the store. It takes 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.

Boric acid is the most economical type of borate available. We are all learning ways to stretch chlorine and keep water quality good. Borates are just one of many ways.


Terry Arko
HASA Inc