Phosphates and Salt Systems: Why They Don’t Mix

Salt water chlorination systems for commercial swimming pools in Fayetteville provide pool owners with clean, comfortable water without the unending maintenance that traditional chlorine pools demand. Salt systems are simple to operate and a pleasure to own, but they do have an enemy: phosphates. Phosphates are compounds of phosphorous ions and other elements, such as sodium, calcium, or potassium, and they are everywhere. To help us better understand the battle between salt systems and phosphates, let’s first consider how salt systems work.

How a Salt System Works

Salt systems, such as the IC40 Pentair salt system, create chlorine using electrolysis. Water containing salt (NaCl) in a concentration of at least 3000 ppm (parts per million) enters into the pool’s chlorine generator and passes through the salt cell. The cell is where electrolysis takes place. During electrolysis, a low-voltage electrical current passes between two electrodes. One electrode, the anode, is positively charged and the other, the cathode, is negatively charged. When the salty water molecules pass between these two oppositely charged electrodes, the molecules are pulled apart, or split. The split creates hydrogen gas and hypochlorous acid. The hydrogen gas leaves the pool in bubbles and the hypochlorous acid, or free available chlorine, sanitizes the swimming pool water, reverts back to salt, and the process begins again.

Keeping in mind this basic understanding of how an IC40 Pentair salt system works, there are basically three things that can cause the system to fail: insufficient power to the salt cell, insufficient salt in the system, or compromised electrodes. Two of these three reasons for failure—insufficient salt and compromised electrodes—can be, at least in part, attributed to phosphates.

How Phosphates Interfere with a Salt System

How do phosphates contribute to system failure? Let’s look at each failure individually.

Insufficient Salt—Why would a closed system that had plenty of salt to function properly one day have insufficient salt the next? Every pool has a bit of algae, which chlorine works to kill. Algae grows, chlorine kills it, and balance is maintained. However, phosphates are algae food. If the phosphate level in the water grows above a normal level, the algae then has more food and can grow faster than normal, and then the existing chlorine is insufficient to kill the higher level of algae. Suddenly, your pool is filled with algae and the chlorine level has dropped, not because your pool created less chlorine, but because more chlorine was used to kill the algae and less was left to sanitize the water. Thus, high phosphate levels “cause” insufficient salt.

Compromised Electrodes—Electrolysis is the key to a functioning salt system. The salt cell and electrodes need to be clean and free from corrosion or other interference in order to allow the electrical current to flow freely and do its job. Some phosphates are known to adhere to metal. A coating of phosphates on the electrodes can disrupt the electrical current and slow down the electrolysis.

Since phosphates are the enemy to a clean, well-functioning pool, how can you keep them out of your water? This is no easy task, as phosphates are everywhere. Here a few tips from swimming pool contractors that can help you maintain critical balance in your pool:

  • Remove leaves and other debris promptly.
  • Avoid using yard care products such as fertilizers that contain phosphates.
  • Have swimmers rinse before entering the pool to remove hair products, lotions, etc.
  • Monitor the pH level of your pool carefully and keep it within the acceptable range.
  • Avoid introducing scale and stain products to your pool that contain phosphates.
  • Test your pool’s phosphate level periodically and use a phosphate removal product if the phosphate level exceeds 1000 ppm (parts per million).

We have had the privilege of being awarded more than 60 Design Awards in every award category, including custom residential concrete pools, commercial concrete pools, in-ground vinyl liner pools, and major renovations. Hilltop was named one of the “Top 50 Pool Builders in the USA” by Pool and Spa News in 2013-2017. Pool builders across the United States were evaluated in several areas, including the total number of pools built, customer service, certifications, industry involvement, employee retention, as well as advertising and social media presence. Our company was also nationally recognized for customer service and social media. We were the only Georgia company on the list in 2016 and 2017!

We would consider it a privilege to design and construct your project and have you as a member of our “Hilltop Family.”