Question: what carpet cleaning solution is the best?
Answer: Please read our wiki article on “How Cleaning Agents Work” its long but the short version is you need to match the cleaning solution to how the dirt is bonded to the carpet. so you remember the science class about negative and positive, well the really amazing thing about cleaning solutions is that its part of the emulsification process. pH plays a part as well, you dont want to unlock colour as it will run (wool). Always stick to what it instructs you on the label as far as dilutions. If your DIYing just remember it far better to go over a carpet let it dry and clean again than over wet your carpet.
Most of the dirt in a carpet is dry so spending time going over and over with a vacuum will remove much of the dirt. A great way to tell when your done is keep empting the vacuum.
Pre spraying a carpet with a fine mist of the diluted solution and rack it in and then leaving it will give time for the cleaning solution to work. then just follow up with clean water in your carpet cleaning machine.