Apparatus and methods for purifying the water in spas or hot tubs are provided. Such apparatus include an ozone generator sized and adapted to purify the water in a spa or jetted tub, the ozone generator including a chip electrode assembly adapted to produce ozone from air using an electric discharge, a housing structured to permit visual inspection of the chip electrode in the housing, a power supply assembly, and a transfer assembly cooperating with said ozone generator to pass ozone produced by the ozone generator to the water in the spa or jetted tub. The chip electrode assembly is removably secured to and separately enclosed from the power supply assembly and is adapted to be easily, manually replaceable.