What are phosphates?

Phosphates & Nitrogen are 2 naturally occurring elements in nature. Phosphorous is a mineral & nitrogen is a gas. In nature, they don’t cause or contribute to pool problems. However when they are “added” to the pool water, problems can arise — especially in a poorly maintained situation. The two most significant problems are moderate to severe algae blooms and chlorine demand. Both elements are essentially set up as a buffet table for any algae to just come, eat & thrive.

Phosphates typically come into the pool from lawn care products; fertilizers, sprays, etc. Phosphates can also come from dead skin cells! (Therefore, another good reason to shower before entering the pool.) These lawn care products can be brought in from people walking on freshly treated areas where they are literally walked into the pool. They can also “drift” in when sprayed or just due to a windy day. Remember, phosphates can come from your yard, your neighbor’s yard or even from someone you don’t even know who lives 3 blocks away. Phosphates (or forms of phosphorous) are often added directly into pools (yes!) in the form of “metal removers” and “stain control” chemicals – all pool sequestering or chelating products contain phosphorous.

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Nitrogen can also come into your pool from lawn care products, but more typical, it’s a case of sweat (shower before using the pool), urine (use the facilities before going into the pool) or other types of ammonia (ammonia is comprised of Nitrogen & Hydrogen – NH4). If your local water supplier is using chloramines to sanitize the water, then large amounts of ammonia & therefore nitrogen are getting into the water. Algae loves both nitrogen AND phosphates (phosphorous).

With either Phosphates, Nitrites or Nitrates present, as long as a good, solid chlorine or bromine level is maintained, there normally isn’t a problem. However, when the chlorine is stressed out due to high bather loads, parties, rainstorms, etc. or if there is an existing chlorine demand problem, phosphates & nitrates just feed right into any algae present & the problem worsens significantly.

Treating the problem:

  1. Maintain good water balance – pH 7.2 – 7.6, total alkalinity 80 – 120 ppm, calcium hardness 200 – 250 ppm.

  2. Maintain a good chlorine or bromine residual in the water.

  3. Shock the pool and add algicide weekly.

  4. Have a chlorine demand test done twice per season. If a chlorine demand exists, treat it thoroughly and aggressively.

  5. Make sure swimmers & bathers shower before using the pool.

  6. If you know or suspect phosphates have been introduced into the pool, PhosFree® from Natural Chemistry® is a great product that will remove the phosphates from the pool water, thereby depriving the algae of one of it’s significant food sources. Some customers like using this product for “peace of mind.”

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