Balancing water chemistry is one of the most important pillars of pool care and maintenance. While chlorine and pH tend to dominate the conversation, optimal phosphate levels can be just as vital. Today, we’re talking about phosphate remover for pools, so you can better understand how it works and when you should use it!
What, exactly, do phosphates do to a swimming pool?
Are phosphates really that bad for your pool? Here’s an overview of how they impact water quality:
Food for algae
Phosphorus is an essential nutrient for all plant life, including algae. Algae feed on these compounds, which enable exponential growth. Unfortunately, even a pool with crystal-clear water can have a high phosphate content. If sanitizer levels drop, these conditions become perfect for an algae bloom.
Drain on your sanitizer
As algae reproduce, chlorine and other sanitizers must work even harder to kill it, causing sanitizer levels to plummet quickly.
Pools with consistently high phosphate readings can be increasingly difficult and expensive to maintain without a phosphate remover, as chlorine must constantly fight new algae rather than clean the water of other impurities. In turn, you must raise levels of hypochlorite (the active sanitizing agent in free chlorine) to compensate for the loss.
Common phosphate sources
Phosphates are naturally occurring compounds found throughout your home and the environment in both living and non-living things, so it’s no surprise they often make their way into swimming pools. Common sources include:
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Leaves, grass clippings, pollen, and other organic debris
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Rainwater and storm runoff
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Fertilizers
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Body oils, sweat, and topical products from swimmers
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Certain pool chemicals
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Municipal and well-water sources
How does a phosphate remover for pools work?
A phosphate remover for pools uses a process called chemical precipitation to remove phosphorus compounds. Let’s take a closer look at how it works.
Binding agent
Unlike older phosphate removers like aluminum sulfate, which were harder to use and adversely affected water quality, most modern formulas rely on lanthanum. Once applied to the pool, the lanthanum ions bind to phosphate ions, forming an insoluble compound called lanthanum phosphate.
In other words, a phosphate remover for pools doesn’t destroy phosphates – it simply converts them to a larger, solid mass.
Filtration
Following application, you may be left with larger particles floating around in your pool. So, how do you get rid of them? This is where your filtration system comes into play. Those newly formed compounds will remain in the water column until they’re captured by your filter.
For the best results, run your pump for several hours to several days. Then clean or backwash your filter to eliminate debris and maintain optimal performance. You might be surprised by how much solid material your filter has collected.
Water clarity
No one wants to see cloudy water in their swimming pool, but after applying a phosphate remover, it’s actually a positive sign that the treatment is working as intended. That murky, hazy appearance is caused by the binding process and intensifies as phosphate particles become larger.
When should you use phosphate remover in your pool?
Balanced water chemistry requires a strategic approach. Here are a few ways to determine when your pool, spa, or hot tub needs a phosphate remover:
High phosphate readings
Water testing supplies should be your first line of defense whenever your pool chemistry is in question. However, interpreting the results can be a little tricky. Unlike free chlorine, alkalinity, and pH, there’s no universal standard outlining when a reading is considered too high. Some people use a phosphate remover when levels exceed 500 parts per billion, while others treat any pool that tests above 125 ppb.
Seasonal milestones
Phosphate readings may peak predictably at certain times of the year, including:
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At the beginning of pool season
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During peak pollen season
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In autumn when leaf litter accumulates in the pool
It’s also a good idea to test phosphate levels following any heavy rainstorm or flooding and after refilling your pool. You might also keep an enzyme treatment on hand to break down organic contaminants before they fully decompose, helping you prevent algae blooms down the line.
Stubborn algae blooms
Algae that keeps returning despite maintaining balanced water chemistry and sanitizer levels may indicate elevated phosphates as part of the problem. Remember, phosphate remover won’t kill existing algae, but it will eliminate a primary food source that keeps it happy. But when it’s used alongside proper chlorine levels, circulation, and filtration, it can help prevent algae growth.
Here’s a step-by-step guide to effectively tackling stubborn algae blooms:
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Scrub affected surfaces to dislodge stuck-on algae.
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Use an extra-strength pool shock to destroy existing algae.
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Clean or backwash the filter to eliminate any traces of algae.
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Apply a phosphate remover to reduce the algae’s food source and help prevent future blooms.
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