Phosphates In Pools: What They Are & Why They’re A Problem
When it comes to pool care, you’re probably familiar with chlorine, pH balance, and filtration. But there’s another factor that often slips under the radar: phosphates.
What Are Phosphates?
Phosphates are natural compounds containing phosphorus. They often sneak into your pool from everyday sources like:
Garden fertilizers or lawn runoff after rain
Leaves, dirt, and organic debris
Swimmer products such as lotions or soaps
Even your household tap water in some areas
On their own, phosphates aren’t dangerous to swimmers. But they are a problem for your pool water.
Why Are Phosphates a Problem?
Think of phosphates as fertilizer for algae. Just like plants in the garden need nutrients to grow, algae thrive when phosphates are present. Even if your chlorine levels are balanced, high phosphate levels make it much harder to keep algae under control.
Here’s what can happen when phosphates build up:
Fast salt depletion and greater strain on the system
Algae blooms, leading to green or cloudy water
Increased chlorine consumption, meaning you’ll need to add more
Higher chemical and maintenance costs
A pool that constantly feels like it’s “on the edge” of turning green
What’s the Ideal Phosphate Level?
Phosphates are measured in parts per billion (ppb). As a guide:
Below 100 ppb: Ideal, minimal risk
500 ppb or more: Algae may start to take hold
1,000+ ppb: High risk of persistent algae issues
How to Control Phosphates in Your Pool
The good news? Phosphates are manageable. Here’s how:
Prevent debris – Skim leaves, clean filters, and keep organic material out of the water.
Maintain water balance – Correct chlorine, pH, and alkalinity levels help reduce algae growth.
Use a phosphate remover – If levels are high, a lanthanum-based phosphate remover will bind and eliminate them.
Regular testing – Routine water tests help you spot rising phosphate levels before they cause problems.
Final Word
Phosphates might be invisible, but their impact on your pool water is anything but. By keeping levels under control, you’ll make it easier for your chlorine to do its job, reduce algae problems, and save money on chemicals in the long run.