The amount of time it takes to pull a full vacuum on a BHO Buster system varies depending on the CFM of the pump as well as the size of the extractor. If you have a 3-5 CFM pump, it shouldn’t take you more than 7-8 minutes to pull a full vacuum on a 1 lb BHO Buster . Using the same 3-5 CFM pumps, pulling a full vacuum on the 2 lb BHO Buster unit may take roughly 10-12 minutes. For the 5 lb units you’ll need to use a vacuum pump which is closer to 7 CFM. With the larger pump, it should take no longer than 10-15 minutes to pull a full vacuum on the 5 lb unit or the 8-10 lb unit.