Cleaning Trex Deck

[GolfVenture]

Any recommendations on how to get a Trex Deck really clean. Currently I just use my pressure washer. It gets it clean ok, but there are still some dirt left behind. My Pressure Washer is rated at 3100 psi.

[Prairiehammer]

If it is an original Trex decking, it is likely to have mold/mildew and stains caused by the reaction of the high tannin oak sawdust sometimes used and either iron from the screws/nails or even a reaction to iron in the wash water. Oxalic acid may be required to remove the iron/tannin stain. Try a bleach made for decks to remove the mold/mildew stains. Some dark stains have been traced to environmental fallout (air pollution).

How old is the deck? Being you are in the PNW, does the deck remain damp for long periods? Is there green stains from algae? Use an algaecide, if so.

Some of the stains common to Trex are not just on the surface and a high pressure wash without detergents, algaecide, oxalic acid or bleach will not remove those deep down discolorations.