Calcium Phosphate - Wayne Ivusich

Picture this: you're maintaining a beautiful heated pool, everything seems perfect, but suddenly you notice stubborn white scaling that's nearly impossible to remove. Welcome to the world of calcium phosphate—one of the most frustrating challenges pool professionals face. In this comprehensive guide, we'll explore what causes this troublesome compound to form and how you can prevent and treat it.

Understanding Phosphates: The Foundation of the Problem

Before diving into calcium phosphate specifically, it's crucial to understand what phosphates are and how they infiltrate our pools. Phosphates exist in three primary forms: orthophosphate, metaphosphate (sometimes called polyphosphate), and organic phosphate. While all three can impact water quality, organic phosphate is particularly problematic for pool maintenance.

The primary source of phosphates in swimming pool or recreational water comes from runoff of fertilizer used in heavily landscaped pools. If you have your lawn chemically treated, it's probably going to have phosphates in it, but they get into the pool water by unscrupulous landscapers.

— Wayne Ivusich, Talking Pools Podcast

Anyone who has serviced pools knows the frustration Wayne describes—watching landscapers mow lawns while grass clippings blow directly into the pool water. This scenario introduces phosphates that feed algae growth and create cloudy water conditions. The good news? Phosphates can be removed using lanthanum chloride-based products, regardless of the brand name on the bottle.

The Triple Threat: When Calcium Phosphate Forms

Calcium phosphate doesn't just appear randomly—it requires a perfect storm of three specific conditions working together. Understanding these conditions is key to prevention and early intervention.

Calcium phosphate actually appears as a scale in recreational water, especially in recreational water, where two things are happening. Well, three things are happening. One, there's a phosphate level in your pool greater than 125 parts per billion. Two, the temperature of the water is warm to hot, which means heated pools, spas, hot tubs, things of that nature. The third one is a high calcium level, high calcium carbonate level.

— Wayne Ivusich, Talking Pools Podcast

Let's break down each component of this triple threat:

• High Phosphate Levels: When phosphates exceed 125 parts per billion
• Elevated Temperature: Water temperatures above 85°F (particularly common in spas and heated pools)
• High Calcium Hardness: Typically in the 600+ ppm range

When these three factors converge, phosphates bond with calcium to create an incredibly stubborn white scaling that can be nearly impossible to remove without mechanical intervention.

The Consequences: Why Calcium Phosphate Is a Pool Professional's Nightmare

Calcium phosphate scaling isn't just an aesthetic issue—it's a maintenance nightmare that can significantly impact pool equipment and surfaces. The scaling forms a bond so strong that standard chemical treatments often prove ineffective.

The phosphate actually attaches itself to calcium. And what it will do is cause this white scaling that's really, really tough to get rid of. I mean, you almost have to chisel it off if you let it, if you ignore it and just let it kind of grow. And it's a pain in the butt. It really is.

— Wayne Ivusich, Talking Pools Podcast

This scaling can:

• Damage pool surfaces and equipment
• Reduce circulation efficiency
• Create rough surfaces that harbor bacteria
• Require expensive remediation or resurfacing

The key takeaway? Prevention is far more cost-effective than treatment after the fact.

Prevention and Treatment Strategies

Fortunately, understanding the three-factor requirement for calcium phosphate formation provides clear prevention strategies. The most effective approach involves controlling the factors within your influence.

Phosphate Management

Regular phosphate testing and treatment should be part of your standard maintenance routine. Use lanthanum chloride-based phosphate removers when levels approach 125 ppb. The frequency of treatment will depend on your specific environment—some pools may need weekly treatment, while others might only require monthly or occasional intervention.

Calcium Hardness Control

Monitor calcium hardness levels closely, especially in heated pools. When levels exceed 600 ppm, consider partial drain and refill procedures to dilute the calcium concentration. This is particularly important for spas and heated pools where evaporation concentrates minerals.

Temperature Considerations

While you can't always control water temperature (especially in spas), awareness of the increased risk in heated water helps prioritize monitoring of the other two factors.

Alkalinity Testing: Getting Accurate Results

Proper water testing is fundamental to preventing calcium phosphate formation, but alkalinity testing can be tricky. Understanding the process helps ensure accurate results that inform treatment decisions.

Remember there is no such thing as total alkalinity. Well, excuse me. There is a thing called alkalinity, total alkalinity, but alkalinity is comprised of a lot of different things. So you've got bicarbonates, carbonates, sulfates, a number of other minor players. And cyanuric acid is the big one that comprise total alkalinity.

— Wayne Ivusich, Talking Pools Podcast

The alkalinity test is an acid-base titration that should produce a color change from green to red. However, high chlorine or bromine levels can interfere with this process, causing unusual color developments like blue, yellow, or blue-to-yellow transitions.

Troubleshooting Alkalinity Test Interference

When you encounter unusual colors during alkalinity testing:

• Double the amount of chlorine neutralizer (sodium thiosulfate)
• If using two drops initially, increase to four drops
• Adding extra thiosulfate won't harm the test accuracy
• Wait at least one full water turnover after shocking before testing

Expert Resources and Professional Development

Wayne references an excellent article by Terry Arko that appeared in Pool & Spa News, providing additional technical depth on calcium phosphate issues. Staying current with industry publications and expert insights is crucial for professional development.

My good friend Terry Arko with NSPF wrote a really, really, really good article about calcium phosphate that came out in Pool and Spa News a while ago. If you Google calcium phosphate and recreational water, you'll find that. And it's a triple threat. And it was really well written. Terry knows his stuff.

— Wayne Ivusich, Talking Pools Podcast

Conclusion: Prevention Through Understanding

Calcium phosphate formation represents one of the more challenging issues in pool maintenance, but it's entirely preventable through proper understanding and proactive management. Remember the triple threat: phosphates above 125 ppb, high calcium hardness (600+ ppm), and warm water temperatures create the perfect storm for calcium phosphate scaling.

The key to success lies in regular testing, understanding the chemistry behind the problems, and maintaining balanced water conditions before issues develop. By controlling phosphate levels through regular treatment, managing calcium hardness through dilution when necessary, and staying vigilant with heated pools and spas, you can prevent the headaches associated with calcium phosphate scaling.

Most importantly, invest in proper testing procedures and don't rush the process—wait for full water turnover after treatments and use adequate neutralizer to ensure accurate test results. Prevention will always be more cost-effective than remediation, and your clients will appreciate the proactive approach to maintaining their aquatic investments.

Episode Chapters

• 00:00 Introduction and Weather Update
• 03:15 What is Phosphate?
• 08:30 Calcium Phosphate Formation Conditions
• 15:45 Treatment and Prevention Strategies
• 22:10 Alkalinity Testing Issues
• 28:00 Troubleshooting Test Interference