This cleaner worked so well on our Trex deck that had been ignored for many years. It removed all the unsightly mold and spotted areas. It was quite time consuming preparing the area as we have a high deck over a cement slab with furniture underneath. All this had to be moved. When rinsing the deck we needed a person under it with a hose spraying everything, consequently getting soaked trying to hose the underside of the Trex. No matter how much we sprayed it still left white streaks. The top of the deck looked great, but sitting under it, it's quite unsightly. It's too high to reach with a brush to try and scrub while hosing. So, while the cleaner is quite effective, it is too hard to repeat the process for upkeep with only my husband and me tackling it.