If you pressure wash a patio around a swimming pool and it still feels slippery, it’s usually because the surface hasn’t been fully cleaned at a deeper level, and a thin layer of biofilm remains.
This invisible layer is made up of organic growth that isn’t always removed with basic cleaning. When the surface becomes wet, it creates a slippery film underfoot — even if the patio looks clean.
To fully resolve the issue, the surface needs to be properly treated and cleaned using the correct combination of methods to remove contamination at the source, not just the visible dirt.