Bissells' review: FREE! BISSELL® Clean + Allergen formula works in all BISSELL® upright carpet cleaners to remove deep down odors, dirt and allergens from carpet, upholstery, area rugs, and similar soft surfaces. It also helps remove pollen, pet and dust mite waste allergens. Finally purchased our ProHeat 2X® Revolution® Pet Pro Carpet Cleaner, initially used BISSELL® Clean + Allergen formula on all of our carpets, Did a great job, however, I did need to go over a few areas with BISSELL® PET PRO OXY Urine Eliminator formula and was able to remove even more, but not all. I also had a problem with a leaky dirty water tank, and it wasn't even close to the water mark where you're supposed to empty the tank. Learned to keep a towel handy for any leaks, or drips along with having a bucket handy to empty the dirty water tank. Otherwise, very happy with my Bissell! My carpets look great!!!