High Phosphates in Pool Water – 19 things to know

At Certified Pool Pros, we understand the importance of maintaining a pristine swimming pool for our customers. One often overlooked factor that significantly impacts water quality is the presence of phosphates. Though seemingly harmless, these compounds can act as a hidden enemy by fueling algae growth in your pool. This blog post will help you understand what phosphates are, how they enter your pool, and how they contribute to the dreaded algae bloom. With this knowledge, we aim to help you maintain a clear, inviting pool.

Phosphates in pool

What Are Phosphates?

Phosphates are chemical compounds containing the element phosphorus, a nutrient necessary for the growth of plants and algae. Phosphates in your pool primarily exist in the form of orthophosphates, which are highly soluble in water. These compounds do not harm humans or pets swimming in the pool. Phosphates don’t cause algae, but high phosphate levels are a food source, and they create an environment conducive to its growth.

Sources of Phosphates in Pools

Phosphates can enter pool water from various sources. Understanding these sources is crucial for effectively managing and preventing high phosphate buildup. Here are some common ways phosphates find their way into your pool:

1. Organic Debris:
Leaves, grass clippings, and other organic matter can introduce phosphates into the pool as they decompose. This is especially common in outdoor pools surrounded by vegetation.

2. Rainwater and Runoff:
Rain can carry phosphates from the atmosphere into your pool, while runoff from surrounding areas can wash in fertilizers and other phosphate-containing materials.

3. Fertilizers:
Fertilizers used in landscaping around the pool can be a significant source of phosphates. When these fertilizers are washed into the pool by rain or irrigation, they can elevate phosphate readings.

4. Pool Chemicals and Cleaners:
Some pool maintenance products, such as certain types of algaecides, contain phosphates. Using these products can inadvertently increase phosphate in your pool.

5. Swimmers:
Sunscreens, lotions, and other personal care products used by swimmers can introduce phosphates into the pool water.

6. Fill Water:
The water used to fill your pool may already contain phosphates, especially if sourced from wells or municipal supplies treated with polyphosphates.

How Phosphates Fuel Algae Growth

Algae are simple aquatic organisms that thrive in nutrient-rich environments. While algae need several nutrients to grow, phosphorus is one of the most crucial. Even in small quantities, phosphates can provide the necessary fuel for algae to bloom.

7. Nutrient Supply:
Phosphates serve as a primary nutrient source for algae. When phosphates are present in pool water, they act as a food source for algae, allowing it to grow rapidly.

8. Favorable Conditions:
Warm temperatures, sunlight—both of which we have an abundance of in Orlando—and stagnant water can create ideal conditions for algae growth. When these conditions are met, and phosphates are present, they can multiply quickly, leading to noticeable blooms.

9. Resistance to Chlorine:
Algae that feed on phosphates can develop a biofilm, which protects them from chlorine and other sanitizers. This biofilm makes it harder to eradicate the algae once it has taken hold.

Algae Blooms

Algae blooms can negatively affect your pool, both aesthetically and practically. Here are some of the key issues:

Phosphates in pool - Algae

10. Reduced Water Clarity:
Algae can turn clear pool water cloudy or give it a greenish tint, making it uninviting and unpleasant for swimmers.

11. Slippery Surfaces:
Algae can make pool surfaces slippery, creating a safety hazard for swimmers.

12. Increased Chemical Demand:
Algae consume chlorine and other sanitizers, reducing their effectiveness and increasing the amount of chemicals needed to maintain balanced water chemistry.

13. Clogged Filters:
Algae can clog pool filters, reducing their efficiency and requiring more frequent cleaning or replacement.

Managing Phosphates to Prevent Algae Growth

Preventing and managing phosphate levels in your pool is essential to control algae growth. At Certified Pool Pros, we take proactive steps during our weekly maintenance visits to keep your pool in top condition. Here are some strategies to keep phosphate levels in check:

14. Regular Testing:
During our visits, we regularly test your pool water level of phosphates. If you prefer to test on your own between visits, many pool supply stores offer easy-to-use phosphate testing kits.

15. Routine Cleaning:
Our team promptly removes organic debris from your pool and surrounding areas to minimize phosphate introduction. Between our visits, you can help by regularly skimming the pool surface and cleaning out skimmer baskets.

16. Removing Phosphates from your pool:
If phosphate levels are high, we use phosphate removers that bind with phosphates, making them easier to filter out of the water. We recommend not using any additional products without consulting us first to ensure compatibility with your pool’s maintenance plan.

17. Maintain Proper Water Chemistry:
Our service includes keeping your pool’s pH, chlorine level, and other chemical levels balanced, which helps prevent algae from growing. If you notice any imbalance, let us know immediately so we can address it during our next visit.

18. Control Sources of Phosphates:
Be mindful of the products you and your swimmers use in and around the pool. Choose phosphate-free alternatives when possible, and inform us of any changes in product use so we can adjust our maintenance plan accordingly.

19. Monitor Fill Water:
If you have a phosphate issue, we may test the water used to fill your pool for phosphates. 

Phosphates in pool water may seem minor, but their impact on algae growth and overall pool maintenance can be significant. By understanding how phosphates enter your pool and how they contribute to algae blooms, we at Certified Pool Pros can help you take proactive steps to manage and reduce phosphate levels. Regular testing, routine cleaning, and using appropriate chemicals are all part of an effective strategy to keep your pool clear and inviting. Remember, a little attention to phosphates can go a long way in maintaining a beautiful, algae-free swimming pool.

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