FAQ Search Select a Category Cleaning Formulas Cleaning Tips Corporate Deep Cleaners FAQ Hard Floor Cleaners Parts and Accessories Steam Sweepers Vacuums Warranty Web Site and/or go Why is my Upright Deep Cleaner Foaming? Answer: What formula are you using? We recommend only using BISSELL Upright Deep Cleaning formula. Make sure you aren't using any manual formula in the machine because it will foam over. Related Questions Water is coming out the side vents. What should I do? My Little Green 1720,1725 is leaking from the bottom. What can I do to correct this? My 1720 Series Little Green® has no power. What can I do? My 1720 Series Little Green® is leaking. What should I check?