Green Pools and Phosphates: What You Need to Know
If you’ve been battling green, murky pool water—even after shocking and scrubbing—it’s time to talk about a common pool water contaminant: phosphates.
Phosphates are organic and inorganic compounds that are everywhere. Organic phosphates are in fertilizers, garden runoff, and pollen. Inorganic phosphates are in pool chemicals used to prevent scale and stains. In your pool, phosphates act as fertilizer for algae. So when phosphate levels rise, algae thrives.
In Coachella Valley, we see phosphate levels spike after palm tree blooming seasons, as pools fill with flower pollen that clogs baskets and filters and prevents water flow.
Let’s break down what phosphates are, why they cause green pools, and how you can keep them under control.
🌿 What Are Phosphates and Where Do They Come From?
Phosphates are naturally occurring compounds that contain phosphorus. While they’re great for growing plants, they’re terrible for pool water. Common sources of phosphates in pools include:
Lawn fertilizer or garden runoff
Decaying leaves and organic debris
Swimmer products like hair conditioners and sunscreen
Body oils and sweat
Pollen and rainwater runoff
Once in your pool, phosphates don’t just sit there. They feed algae, helping it grow faster than your chlorine can kill it.
🟢How Phosphates Turn Your Pool Green
Phosphates play a role in algae growth and poor water clarity through:
Algae Fuel: Phosphates act like fertilizer for algae, giving them everything they need to multiply quickly.
Chlorine Inefficiency: Phosphate levels feed algae faster than chlorine can kill algae, making it impossible for chlorine to keep the water sanitized and clear.
If your pool keeps turning green no matter how often you shock it, phosphates are likely to blame.
🧪 How to Test for Phosphates in Your Pool
Most basic pool chemistry kits don’t test for phosphates. You'll need a specialized phosphate test kit—typically measured in parts per billion (ppb), not million.
Phosphate levels above 300 ppb can start to cause algae issues.
Anything above 500 ppb nearly guarantees a green pool.
At RB Pools, we routinely test phosphate levels for our clients, especially those struggling with persistent algae or green water.
🔧 How to Remove Phosphates from Pool Water
While chlorine can kill algae, it doesn't remove phosphates. Here’s the step-by-step process our team recommends to eliminate phosphates:
Test phosphate levels using a reliable phosphate test kit.
Apply a phosphate remover. This is a liquid solution that binds to phosphates and makes them drop to the bottom of the pool.
Run the pool filter for 24–48 hours. You pool will be white and cloudy during this treatment.
Clean the filter and vacuum the pool to remove phosphates that the phosphate treatment bonded to.
Re-test phosphate levels and repeat treatment if necessary.
Shock the pool with chlorine to kill off any remaining algae.
🛡️ How to Prevent Phosphates from Returning
While you can’t prevent phosphates entirely, there are ways to limit their accumulation:
Shower before swimming: Hair products and body oils carry phosphates into the water.
Keep landscaping tidy: Keep bushes trimmed back and away from pools. Avoid using phosphate-based fertilizers near the pool. Make sure rainwater and irrigation don’t wash soil or fertilizer into the pool.
Remove debris promptly: Leaves, dirt, and pollen all break down into phosphate-rich matter. Clean your skimmer and pump baskets weekly.
Schedule routine testing: At RB Pools we test each summer after the palm tree blooming season, and also throughout the year if your pool chlorine demands are unusually high.
💬 Frequently Asked Questions
Can chlorine remove high phosphate levels?
No. Chlorine kills algae, but it does nothing to remove phosphate from your pool water.
My pool feels slimy—could that be from phosphates?
Yes. Phosphates feed algae, which can cause slimy, green deposits on pool walls and floors.
Can I prevent phosphates entirely?
Not completely, but with proper care and professional maintenance, you can manage levels and avoid green pool water.
💧 Stop the Green Pool Cycle with RB Pools
Dealing with algae over and over again is exhausting and expensive. At RB Pools, we specialize in identifying and resolving the root causes of pool water issues, including persistent phosphate contamination.
Whether you need weekly maintenance or a complete pool remodel, our team brings expert-level care and unmatched craftsmanship to every backyard.
📞 Call or text: (760) 397-5141
📷 Follow us on Instagram: @RB_Pools for design inspiration and past project showcases.