TLDR
Yes, you can power wash a gunite pool, but with important precautions. Use low pressure (1500-2000 PSI maximum), keep the nozzle at least 12 inches from the surface, and use a wide spray pattern. High pressure can damage plaster and grout. For routine cleaning, brushing is gentler and often sufficient.
When Power Washing Makes Sense
Power washing is most appropriate for deep cleaning when your pool is drained, particularly before resurfacing or to remove stubborn stains and algae buildup that regular brushing can't handle. It's effective for removing calcium deposits, black algae spots, and years of accumulated grime from neglected pools. However, it shouldn't be your go-to cleaning method for routine maintenance.
The key is using the right pressure. Standard pressure washers deliver 2500-3500 PSI, which is too aggressive for pool plaster and can erode the surface, create pitting, or damage grout lines. You need to dial down to 1500-2000 PSI maximum and use a 25-40 degree nozzle for a wider, gentler spray pattern. Keep the nozzle moving constantly and maintain at least 12 inches of distance from the plaster surface. Never hold the spray in one spot—this can create divots and permanent damage.
Better Alternatives for Regular Maintenance
For routine cleaning, stick with traditional methods. Regular brushing with a stiff pool brush effectively removes dirt and prevents algae buildup without any risk of surface damage. Combine brushing with proper chemical balance and your pool stays clean without aggressive techniques. Save power washing for when you drain the pool for major maintenance or when facing serious staining issues that brushing can't resolve. When in doubt, consult a professional pool service—they have the experience to assess whether power washing is necessary and can perform it safely without damaging your investment.
