A chemical dispensing assembly having a base member, a flow chamber, a chemical chamber and a dispensing control conduit, wherein water or other liquid flows through the base member, into the flow chamber, through the dispensing control conduit and out the base member, wherein a small amount of saturated solution retained within the chemical chamber is drawn into the water flow, the chemical chamber being connected below the flow chamber and the volume of the chemical chamber being greater than the volume of the flow chamber. Preferably, the flow chamber is connected to the base member with a bayonet-type connection mechanism, and keys and key slots are provided such that only dedicated flow chambers can be connected to the base member.