First U.S. Phoslock Application Yields Promising Phosphorus Reduction

Aquatechnex Biologists applying Phoslock to strip phosphorus from the system

As lakes age, nutrients that drive aquatic plant and algae growth enter the system from the watershed.  As these nutrients build up, excessive growth of aquatic plant life is the common result.  As lakes are the lowest point on the watershed, these nutrients tend to accumulate and over time the lake moves from a clear water body to a eutrophic algae dominated system.  In many cases nutrient rich lakes shift to a toxic blue green/cyanobacteria community and are seriously degraded.

Phosphorus is generally considered to be the key or limiting nutrient in aquatic systems.  Limiting introduction and/or removing this nutrient from the lake has been a key lake management tool for a number of years.  In lake remediation has generally been performed with Aluminum Sulfate, a product that functions well in this role in many cases. Water quality can however have an impact on efficacy or length of control.

Aquatechnex has been working with an Australian Company, Phoslock, to bring their technology to the United States.  Phoslock is a bentonite clay based compound developed by the Australian Government for this purpose and when applied in conjunction with a plan designed based on the individual conditions in the lake will provide dramatic results.  This is a tool that can be used to re-set the biological clock of the lake by sequestering the phosphorus in the system and controlling release from the lake sediments.

This first Phoslock application was made the first week in November in Southern California to a lake system that was extremely rich in nutrients and has experienced severe algae blooms for a number of years.   Pre treatment sampling was performed to develop a nutrient budget for the lake and calculate a dose rate.  On Nov. 10th the application was performed.

Pre treatment total phosphorus levels (includes algae biomass) were 0.82 mg/l and Ortho-phosphate levels (dissolved or available in the water column) were 0.6 mg/l.  One week post treatment the total phosphorus levels were reduced by about half at 0.43 mg/l and ortho-phosphate (available P) was reduced to No Detect.  As algae drop out of the water column the phosphorus present in those organism are also expected to be locked by Phoslock and the total P levels should come down as well.

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