First and foremost, only use genuine Kirby carpet shampoo with your system. Unscrew the large cap from the shampoo tank and use it to measure carpet shampoo. Do not use the cap from the bottle of the shampoo to measure. For a small room, fill the tank with water to the first line on the side of the tank and add one capful of shampoo. To clean a large room, fill the tank to the third line and add three capfuls of shampoo.