A method and apparatus for obtaining a product chemistry from a product and a fluid is provided. A product is housed within a dispenser. A fluid is introduced through a manifold diffuse member having a plurality of ports. A cover is positioned adjacent the manifold diffuse member and includes a plurality of ports. The cover is able to be adjusted, for example, by rotating the cover, to align and un-align the manifold diffuse ports and the cover ports. This adjustment controls the flow characteristics of the fluid through the manifold diffuse member and cover to control the characteristics of the fluid in contact with the product. The adjustment of the cover to control the flow will provide a generally consistent concentration and erosion rate based upon known relationships between a characteristic of the fluid and the flow of the fluid in relation to the product.