Our Trex deck was so bad, we hired a professional to clean it as whatever we tried didn't work. The person that came out to do the job used CorteClean and it turned out to be an unbelievable transformation. He told us how to order it and to keep our deck looking this good recommended that we do it twice a year but at half strength. This has worked very well and it is an amazing product. We discovered it quite by accident and I do fault Trex for not making their customers aware of the fault of this composite deck. Apparently the Trex decks are made differently today but as ours has been here for about 15 years or so, we had to make do with what was here. We would highly recommend CorteClean and also would encourage users to keep up with the maintenance. This makes it much easier. Also the customer service is outstanding. We were given advice on how to make the job easier and have been very satisfied. Palatine, IL.