Phosphates in Your Pool: What They Are and Why You Don’t Want Them

Your pool water might look clean — but if you’ve got phosphates, you could be unknowingly feeding an unwanted guest:         algae        .

Phosphates are one of the most overlooked issues in pool maintenance. They don’t make the water look green on their own… but they quietly fuel the very thing that does.    

Let’s talk about:

• What phosphates are
• Why they’re bad for your pool
• How they get there
• And most importantly — how to get rid of them

🧪 What Are Phosphates?

Phosphates are nutrients — basically plant food — that enter your pool from the environment. On land, they help plants grow. In water? They help algae grow.

Phosphates themselves are not harmful to humans. But in your pool, they’re a major fuel source for algae blooms. The more phosphates you have, the harder it is to keep your pool clear — especially during hot weather.



❌ Why Are Phosphates Bad for Pools?

While phosphates won’t harm swimmers directly, they’re bad news for pool water because:

1. They Feed Algae        

Phosphates are the one food source for algae. Even a small amount can help algae grow faster — especially if chlorine levels drop or the water gets warm and still.

2. They Make Algae Harder to Kill        

If you have high phosphate levels, even shocking your pool might not be enough. Algae can return quickly if phosphates are still present.

3. They Can Overwork Your Chlorine        

Chlorine has to work harder to fight algae fueled by phosphates. That means you’ll use more chemicals and still struggle with cloudy or green water.

🌱 How Do Phosphates Get Into Your Pool?

They’re sneaky! Phosphates enter your pool through everyday sources like:

• Fertilizer or landscaping runoff
• Rainwater
• Leaves, pollen, and organic debris
• Pool fills with tap water (some water supplies contain phosphates)
• Swimmer contaminants (lotions, soaps, etc.)
• Certain pool chemicals (like some stain removers)

✅ How to Test for Phosphates

You can buy phosphate test kits or strips, or have your pool water tested at a local pool store. Phosphate levels are measured in parts per billion (ppb), and even  100–300 ppb can be enough to fuel algae.


🧹 How to Remove Phosphates From Your Pool

Step 1: Clean Your Pool

• Skim out leaves and debris
• Vacuum the pool

Brush walls and steps to remove algae or residue

Step 2: Use a Phosphate Remover        

Use a phosphate remover (also called a phosphate reducer) designed for pools. These products bind with phosphates so your filter can remove them.

⚠️     Heads-up: Some removers can temporarily cloud your pool — don’t panic, it clears up as your filter does its job.

Step 3: Clean or Backwash Your Filter        

After using a phosphate remover, your filter will trap a lot of particles. Clean it thoroughly to complete the task.

Step 4: Maintain Balanced Water

• Keep chlorine levels in range (1–3 ppm) for the AquaSmart system (0.5-1.0 ppm)
• Keep pH and alkalinity balanced

Shock your pool regularly during hot weather or heavy use

🔁 How to Prevent Phosphates in the First Place

• Don’t let leaves, grass, or debris sit in the water
• Avoid fertilizer near the pool
• Rinse off swimmers before they enter
• Use phosphate-free pool products