Our process of cleaning involves application of oxy-action, a cleaner specifically formulated for cleaning Trex composite decking.
Never use conventional deck cleaners or bleach to clean your composite deck. Although bleach will kill the mildew & mold spores it will not remove them from the surface. Bleach will also kill plants & vegetation surrounding the deck. Oxy-Action is an environmentally safe product that is highly effective in killing mold & mildew spores. It removes them from the surface when used in conjunction with low pressure washing so they don’t become a food source for additional staining.
You don’t have to seal the composite deck surface once cleaned, but I suggest you do seal it to prevent stains from quickly redeveloping. I have had great results sealing trex decking with Surface Saver. This water-based sealer is crystal clear & will not change the natural color of the wood. Avoid using solvent-based sealers because they contain alkyd resins, which are a food source for mold & mildew.
Surface Saver utilizes synthetic resins that offer no food value for future stain growth. It also contains siloxane nano particles, which will form a bond with the composite surface to delay the reaccumlation of mold & mildew. We spray the sealer then brush it into the wood, which creates a friction on the surface, which allows the active ingredients to penetrate deep into the pores of the wood. Once your composite trex decking is sealed with Surface Saver, you will have done a lot to help manage the problem of future staining from mold & mildew.