This is a rug cleaner recipe I use frequently. It also works well to dissolve some oxygen cleaner in hot water and add this to your tank (test on a piece of carpet first). I think rug cleaners are very over priced and have made my own with great results for years.
Rug shampoo mix: Mix 1/4 cup mild detergent or soap, with 1 pint of warm water and 2 tablespoons vinegar. Whip into a stiff foam. First, vacuum the rug thoroughly. Apply the foam and scrub. Let dry, then vacuum again.