DOWN JOHN starts working immediately upon application because the bacteria is live and not dehydrated. Any grease cap or septic odor will be gone in several days, backed up or blocked systems are working again in 2 - 4weeks with leach field operational. Accumulated sludge will be reduced in 4 – 8 weeks depending on its depth. DOWN JOHN bacteria will continually multiply till equilibrium and maximum efficiency is reached in about 8-10 weeks.You will not see bubbles as DOWN JOHN eats up gas and does not contain peroxide but results will be seen in the reduction of septic smell in your house and sludge build up in your system.