Disclosed herein are spacers having baffle designs and perforations for efficiently and effectively separating one or more membrane layers a membrane filtration system. The spacer includes a body formed at least in part by baffles that are interconnected, and the baffles define boundaries of openings or apertures through a thickness direction of the body of the spacer. Alternatively or additionally, passages or perforations may be present in the spacer layer or baffles for fluid flow there through, with the passages and baffles having a numerous different shapes and sizes.