300 Series - Retrofits into existing pools or spas. Operates on pressure side of pump. Uses 1/4” feeder hoses, control valve and fittings. Select Feeder Below: R171016 - 300 Holds 11 large or 98 small tablets. Treats 12,000 to 48,000 gallons. R171022 - 300C Holds 11 large or 98 small tablets. Treats 12,000 to 48,000 gallons with see-through amber body. R171056 - 300-19 Spa feeder includes double-capacity 19 in. chamber. Treats 13,000 to 52,000 gallons. R171066 - 300-29 Spa feeder includes triple-capacity 29 in. chamber. Treats 14,000 to 57,000 gallons.