Abstract: A chlorine compound containing chemical tablet for dissolution into a surrounding body of water which includes an elongated tablet with length longer than thickness having an elongate central section connecting two opposing obliquely tapered ends along a longitudinal axis and an elongate tablet shell encasing the tablet having a corresponding elongate central section connecting two opposing obliquely tapered ends. The ends of the shell have openings therein and form an inwardly sloping and obliquely angled junction with the shell's elongate central section. The encased tablet lies in a skimmer unit on its side along a longitudinal axis and dissolves in a generally uniform and slow rate.