A chemical feeder includes a support plate that is positioned within the housing chamber of the chemical feeder is described. The support plate includes a base plate having an upper surface that has one or more extensions that extend upward from the upper surface. The extensions can, with some embodiments, be in the form of arcuate extensions that can together define an impeller pattern or a spiral extension that defines a spiral channel. The upper surface of the base plate and/or the one or more extensions are adapted to support a solid chemical material thereon. The support plate further includes a plurality of arcuate channel apertures or spiral channel apertures that extend through the base plate. A feed liquid introduced into the housing chamber flows through at least one of the plurality of arcuate/spiral channel apertures and contacts the solid chemical material to form a treated liquid.