Effective Option for Cleaning the Washington, D.C. Reflecting Pool by Removing Algae’s Food Source

The Lincoln Memorial Reflecting Pool is one of the most visible water features in the United States. It also has a very practical water quality problem.

Algae keeps coming back.

The issue is not simply cosmetic. The pool is shallow. It sits in full sun. It warms quickly. It has slow-moving recirculated water. Those are ideal conditions for algae and cyanobacteria growth.

Traditional responses often focus on killing or removing algae after it appears. That can help in the short term, but it does not address the underlying driver.

Algae grows because the water gives it what it needs.

One of the most important nutrients is phosphorus.

Why phosphorus matters

In many freshwater systems, phosphorus acts as the controlling nutrient for algae growth. When phosphorus is available, algae and cyanobacteria can multiply rapidly. When phosphorus is reduced, growth pressure drops.

This matters even more when cyanobacteria dominate the bloom.

Some cyanobacteria can fix their own nitrogen from the atmosphere. That means removing nitrogen alone may not be enough to control growth. If nitrogen is limited, some cyanobacteria can compensate. Phosphorus is harder to work around.

That makes phosphorus the practical control lever.

The chemistry is on our side.

The Reflecting Pool is shallow, warm, and slow-moving. Those are challenging conditions. But they also make it a strong candidate for targeted phosphate removal because the water can be circulated through treatment media and monitored closely.

Where Coralyte media fits

Coral Innovations’ Coralyte media is designed to capture phosphate from water.

That makes it well suited for a recirculating water feature like the Reflecting Pool. Rather than relying only on chemical treatment after algae appears, Coralyte could help remove the nutrient that supports the bloom in the first place.

The concept is simple:

1. Pull water from the existing recirculation loop.

2. Pass a side stream through a Coralyte media skid.

3. Capture phosphate before it continues feeding algae growth.

4. Return treated water to the pool.

5. Track phosphate and chlorophyll before and after treatment.

This approach would not require the pool to be redesigned. It would use the pool’s existing circulation concept and add a polishing step aimed directly at phosphorus.

A practical pilot approach

A pilot system could be run as a temporary skid.

The skid would contain Coralyte media in a vessel or tote system. Water from the pool’s recirculation loop would flow through the media at a controlled rate. Sampling ports would be installed before and after the media bed.

The pilot should track several basic data points:

• Orthophosphate before and after the media

• Total phosphorus before and after treatment

• Chlorophyll-a as an algae indicator

• Turbidity

• pH

• Temperature

• Flow rate

• Media loading over time

The first goal would not be to make a visual promise. The first goal would be to prove the mechanism.

Does Coralyte remove measurable phosphate from the pool water?

Does phosphate reduction correlate with lower chlorophyll levels over time?

How often would the media need to be regenerated or replaced?

Those are the questions a pilot should answer.

Why this is different from treating algae after it blooms

Algaecides and oxidants can reduce visible algae. Filtration can remove suspended solids. Manual cleaning can improve appearance.

Those methods deal with the symptom.

Phosphorus removal targets the cause.

If phosphate remains available in warm, sunlit, slow-moving water, algae pressure will continue. The pool may look better for a short time, but the biological conditions remain in place.

A Coralyte skid would work differently. It would steadily reduce the nutrient that allows new growth to rebound.

That makes it a preventative strategy, not just a cleanup strategy.

The value of before-and-after data

A high-profile site like the Reflecting Pool needs a solution that can be measured.

A Coralyte pilot should be built around transparent data:

• Influent phosphate concentration

• Effluent phosphate concentration

• Percent removal

• Daily phosphorus mass removed

• Chlorophyll trend over time

• Visual condition of the pool

• Media service life

• Operating cost per pound of phosphorus captured

This data would show whether phosphorus removal can shift the pool from recurring algae response to active nutrient control.

A better way to manage visible water features

The Reflecting Pool is not a lake. It is not a stormwater pond. It is a shallow, recirculated public water feature with a known algae problem.

That makes it a practical demonstration site for targeted phosphate removal.

Coralyte media could be installed as a polishing step on the recirculation loop, tested under real operating conditions, and evaluated with straightforward water quality data.

The goal is not to fight algae after every bloom.

The goal is to remove the food source that lets the bloom keep coming back.

For the Reflecting Pool, phosphorus control may be the missing lever.