Choosing the Right Pressure Washer for Algae Removal

 

Algae grow on hot, humid surfaces, and a swimming pool area provides the environment for algae to thrive. The slimy green microorganism is unsightly and can be an injury hazard. While some DIY methods, such as hot water and vinegar, work for minor algae infestation, extensive and stubborn algae growth requires thorough and effective elimination techniques, like using a pressure washer. Fed by water through a garden hose, pressure washers use a vacuum or pump to send the water out through a high-pressure nozzle.

Consider the water pressure and flow when selecting the pressure washer for algae. The two crucial metrics of power washers are gallons per minute (GPM) and pounds per square inch (PSI). GPM determines the surface area covered by the water flow and rinsing power, while PSI indicates the water pressure. The two account for the pressure washer’s cleaning unit (CU) performance.

Dirt comes off easily under 50 PSI, but this does not work for algae removal, especially when lodged in cracks. Surface algae stains require about 1,000 PSI to remove, while stubborn growth calls for between 1,400 and 3,000 PSI. A residential pressure washer typically provides a maximum of 3,000 PSI, while a commercial version peaks at about 4,000. Do note that pressures over 3,000 PSI, typically used to remove rust, will strip a pool deck’s paint or dislodge sealants.

Selecting the pressure washer for algae by the GPM is trickier, but hinges on the area and the cleaning speed. A residential pressure machine with a flow rate of 2 gallons per minute requires more time for the same area of algae growth than a commercial version, which ranges between 6 and 9 gallons per minute. Experts suggest choosing the power washer based on GPM over PSI, as too much pressure can make the machine harder to handle and cause damage.

Considering the proximity to the pool water, the cleaning solution type and delivery mode both matter. While the pressurized water dislodges algae by itself, and does so better than a standard garden hose or broom, an additive such as commercial algae cleaning solution does ease the cleaning process and reduces the chances of recurring growth.

As for the type of machine, experts recommend a downstream injector pressure washer instead of the built-in soap tank type. The former first pressurizes the water, picks the soap, cleaning detergent, or bleach using a vacuum effect, then delivers the mixture to the nozzle. The built-in soap tank mixes the water and detergent first, then passes the solution through a pump and then to the nozzle. This working principle can result in pump damage from household cleaning solutions, even mild soap. Most washers have a “no bleach” caution on their bodywork.

The spray water nozzle on a pressure washer determines suitability for different applications. The types, identified using a nozzle number consisting of four or five digits, guide the user on the application. The first two digits indicate the nozzle spray angle in degrees. The four standard nozzle measures are 0, 15, 25, and 40 degrees. Experts recommend the 25-degree type for removing algae growth from the pool deck.