Borate refers to the borate ion [B(OH) –], which is a form of the chemical element boron. Borate is found in various fruits, vegetables, seawater, and saline lakes, and is also produced from boric acid, a salt known as sodium tetraborate pentahydrate. Borate is used in the pool industry for pH buffering, algae prevention, lowering chlorine demand, UV protection for hypochlorous acid, and making water softer and clearer. However, excessive consumption of boron leads to borate toxicity.
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What is the Chemistry of Borates?
The chemistry of borates involves boric acid, a Lewis acid, acquiring an OH- from water, which increases the H+ (hydrogen ion) and lowers the pH. Borax, a salt of boric acid, dissociates into sodium ion and borate ion in water. The equilibrium between boric acid and the borate ion in solution prevents pH from rising, especially at higher pH values.
What is Sodium Tetraborate Pentahydrate?
Sodium tetraborate pentahydrate is a salt of boric acid with the chemical formula Na B O •5H O. It dissociates into sodium ion (Na+) and borate ion [B(OH) –] when added to water. Sodium tetraborate pentahydrate is similar to borax but requires less quantity compared to borax for the same effect or purpose because sodium tetraborate pentahydrate contains half as much water as borax.
What is the Role of Borate as a pH Buffer?
Borate acts as a pH buffer by resisting changes in pH when acid or alkali are added to the water. Borate prevents pH from rising, especially at higher pH values. Borate, along with total alkalinity (TA) and cyanuric acid (CYA), forms the ideal buffering system against pH changes. Keeping borate at the target level of 50 ppm will stabilize the pH, preventing significant fluctuations.
How do Borates Help in a Salt Water Chlorine Generator (SWG) Pool?
In a Salt Water Chlorine Generator (SWG) pool, borates are beneficial as they slow the rate of pH increase. This reduces the need for frequent acid and bicarb additions. The optimal borate level in an SWG pool is 50-70 ppm.
What are the Benefits of Using Borates?
The benefits of using borates include pH buffering, algae prevention, lower chlorine demand, UV protection for hypochlorous acid, and softer and clearer water. Borates were first introduced to the pool industry in 1984 and have been popularized since then. Borates are stable, they do not decompose or expire. The only way the concentration of borate decreases is through by water loss. The target concentration for borate is 50 ppm.
How Can Borate Help in Algae Prevention?
Borate supports in algae prevention by disrupting algae’s cell wall development, metabolism, and cell division, therefore acting as effective algaestats. Using borates lowers the chlorine demand, as they prevent algae growth. Additionally, borate reduces the necessary amount of free chlorine from 7.5% of CYA to 5.0% . This implies that maintaining up to 80 ppm CYA with only 5% of CYA as free chlorine is possible, while still complying with the EPA’s maximum limit of 4.0 ppm for free chlorine.
Are Borates Effective as Algaestats?
Yes, borates are effective as algaestats. They disrupt algae’s cell wall development, metabolism, and cell division, making them effective in preventing algae growth. Using borates also lowers the chlorine demand in the water.
What are Borate Products and How to Use Them?
Borate products are useful for the maintenance of pool water. The most recommended product is boric acid due to its cost-effectiveness and minimal pH and TA adjustments. Using boric acid involves activating the pump for 24 hours, measuring the required dose of boric acid, and breaking up any clumps. The powder must then be evenly distributed into the water while moving around the pool. If any powder settles at the bottom of the pool, a pool brush is used to help dissolve it. After a period of 12 hours, the pH and alkalinity of the water must be tested and adjusted as necessary.
How to Test Borate in Pool and Spa Water?
Borate in pool and spa water must be maintained at 50 ppm. It is tested after significant water replacement, with monthly testing being sufficient. A testing method is needed to measure borates, and test strips are available from various companies including Lamotte, Insta Test Borate, ITS PoolCheck Borate, Hach Aquachek Borate, and Taylor Technologies. The borate level must be checked monthly and if the level nears 30 ppm, enough borate must be added to increase it to 50-60 ppm.
Why Can’t You Purchase Borate from Pool Stores in California?
In California, borate cannot be purchased from pool stores because it is categorized as a “water modifier” under the “spray adjuvants” pesticide category by California law. This means it must be registered as a pesticide and undergo toxicity, cancer, and exposure tests before approval. The high cost of complying with these regulations discourages pool chemical manufacturers from selling borate. In California, it is possible to buy baking soda and borax at grocery stores for baking and laundry purposes. Boric acid is bought also from home centers to eliminate garden pests. However, California law categorizes these substances as “water modifiers” under the “spray adjuvants” pesticide category. According to the California EPA, any product used to adjust water pH to enhance pesticide performance is subject to the same regulations as a pesticide. Therefore, baking soda and borates must be registered as pesticides in California. They must undergo toxicity, cancer, and exposure tests before approval. Companies selling these products must also pay a usage fee to the state for every pound sold. While baking soda has complied with these regulations, borate has not. Therefore, baking soda, registered as a pesticide, is bought from a pool store in California, but not borate. The high cost of complying with California Pesticide Regulations discourages pool chemical manufacturers from selling borate. However, individuals still purchase borax or boric acid from a lawn and garden store or a home center for personal use in pools or spas.
What is Borate Toxicity?
Borate toxicity refers to the harmful effects of consuming excessive amounts of boron, a chemical element found in various fruits, vegetables, seawater, and saline lakes. The typical boron content in these sources ranges from 160-300 parts per million (ppm).
How does Borate impact pool water balance?
impacts pool water balance by acting as a pH buffer and an algaestat. Borate reduces chlorine consumption and remains in the water, maintaining a stable pH level and preventing algae growth. Borate also slows the rate of pH increase in pools with a Salt Water Chlorine Generator (SWG), reducing the need for frequent acid and bicarb additions. Furthermore, borate lowers the chlorine demand by preventing algae growth, contributing to the overall water balance in the pool.
