A system for forming a subterranean wellbore may include a pump and an additive supply. The pump pumps a drilling fluid into the wellbore while also generating a pressure differential that draws an additive across a supply line connected to the additive supply. The drilling fluid may be a gas or a liquid. A method for forming a wellbore may include drilling the wellbore, circulating a drilling fluid in the wellbore using a pump; and supplying an additive to the drilling fluid by flowing the additive across a supply line using a pressure differential generated by the pump. The pump may generate a vacuum pressure at a supply line outlet and/or create a pressure differential in the supply line. The flow of additive across the supply line may be regulated and/or stopped when the pump is not operating.