Decanted oil is the lowest priced product and the goal is to reduce its yield. The DO’s yield depends largely on the quality of the feedstock and the conversion level. Naphthenic and aromatic feedstocks tend to yield more bottoms than paraffinic feedstocks. If the conversion is in the low to mid-70s, increasing catalyst to oil ratio or using a catalyst with an active matrix can reduce slurry yield. Raising conversion reduces bottoms yield. If the conversion rate is in the 80s, there is little more to be done to reduce the bottoms yield. Other parameters that can reduce the DO product include higher fresh catalyst activity, effective feed atomization, and adequate residence time in the riser.