My carpet was so filthy that I went through the bottle of cleaner I had bought when I rented the machine. I use Simple Green for so many other things, that I thought I would give it a try. It worked like a dream and was better than the cleaner they sell you!!! Like I said, my carpet was filthy, so I did a 1:1 ratio of the Simple Green with water at first. It’s actually pretty powerful stuff, though, so you can change that to a lot less. I think they even have a recommended ratio right on the container for cleaning carpets. Yep, it’s 1 oz of Simple Green to 4 cups of water, or a 1:30 ratio.