What are Phosphates?

What are Phosphates and How Do They Affect Your Swimming Pool?


Sixty percent of pool owners experience two full algae blooms every season. So, what causes these blooms and how can we prevent them?

Algae blooms place a high demand on the chemicals present in your water and cost time and money in clean up. While everyone agrees on how to kill algae once it’s taken over your pool, here we will discuss how to take a proactive approach to preventing anything from blooming in your backyard except for your prized roses!

With that, we’d like to introduce you to phosphates: a biological building block that is constantly being introduced to your water and nourishing algae spores. In this blog, we’ll explain how being proactive with phosphate-fighting chemicals – instead of reactive with huge amounts of chlorine shock and a scrub brush – will help prevent algae blooms and make your sparkling pool water the crown jewel of the Valley Of The Sun.

 Algae and Other Scourges

In order to understand how to defeat algae, you must understand what it needs to survive.

Algae reproduction depends completely on the presence of five key things:


1 Sun

2 Water

3 Air

4 Nitrates

5 Phosphates


Phosphates are compounds of the nonmetallic element phosphorous and are a primary food source for aquatic plants, including all types of algae. Phosphate compounds are broken down into their simplest form, orthophosphates, in one of the following three ways:


1 Oxidation (converting compounds in to oxides)

2 Hydrolysis (decomposition by water)

3 Enzymatic digestion

Regardless of how it happens, if phosphates are allowed to remain present in pool, spa, or pond water, they will be reduced to orthophosphates, which are the only form of phosphates that algae can digest.

Orthophosphate levels should remain below 100-125 ppb (parts per billion). Once levels exceed 200 ppb, algae becomes increasingly resistant to sanitizers, including chlorine shock. Excessive levels of orthophosphate, such as 1,000 ppb or more, should be brought under control with AquaValue Phosphate 3000 ($24.99) or Starver X ($32.99) from any one of our 7 B&L Pools locations

Who Invited Phosphates to the Party, Anyway?

The challenge with phosphates is that they are constantly being introduced into your swimming pool water. They are found in lawn and garden fertilizers, decaying vegetation, municipal water, cosmetic items on bathers, and even other pool chemicals. This means a fresh batch of phosphates enter your water when any of the following occur:

  The wind blows dirt into your pool

  Sprinkler run off from your lawn or landscaping enters your pool

  Your water leveler puts fresh water into your pool

  Leaves, twigs, or bark enters your water

  You use chemicals containing TSP, or any amount of phosphoric, phosphonic or other phosphorous based ingredients to clean your pool

As such, you can never completely remove phosphates. Instead, we refer to it as maintaining a “near zero” level with a long-term solution that includes a blend of using BioGuard Pool Complete ($59.99), regular water testing, correct sanitizer levels and limiting exposure to phosphates.


How to Maintain “Near Zero” Phosphate Levels

Pool Water Testing

To effectively control phosphates, you must be able to measure their presence in your water. We recommend regular water testing at any one of our locations. Regular testing means every week or every other week, or at the first sign of trouble, (cloudy water, visable green or yellow in the water or walls) Also be sure to have your water tested after pool parties, monsoon storms, or windy days. Also note that a pool in the vicinity of golf courses, major roadways and horse properties are susceptible to high phosphate levels.


Regular Pool Maintenance

The preventative measure of limiting phosphate exposure is taken by doing the following:

  Remove leaves and organic material from the water as soon as possible

  Vacuum and clean filters and pump baskets regularly

  Be aware of the phosphate content of cleaners and chemicals used in and around the swimming pool

  Don’t allow drainage from plants or the lawn to enter the pool

Phosphate remover myth buster:

We want to take this opportunity to clear up a myth about phosphate removers: they do not kill existing algae. Once bloomed, only superchlorination and/or an algaecide will do the job.

enjoy their pool or spa immediately after use. Pool Complete delivers highly effective results while being gentle on bathers and the environment.

Questions? customerservice@pooltroubles.com or call (602) 242-5845  * 16427 N Cave Creek Rd, Phoenix, AZ 85032