In most cases, you don’t need any special cleaner. Dish or laundry detergent with some water does fine for most materials, such as polyester or
polypropylene. You can, of course, mix it in a five gallon bucket and use a brush to clean it by hand. But a less time and energy-intensive way is to hose it down using your pressure washer. If you don’t have a pressure washer, you can also use a carpet shampooer. If you go with this method, though, you’ll need to buy a cleaner that is compatible with the machine.