50 Square Foot Rainbow, Waterway Plastics, Custom Molded Products . Note: 50 Square Foot C-4950 is an upgrade to 25 Square Foot C-4326 and C-4625 cartridges. Replacement for: Accent Spas; Acryx-Maax Spas (Canada); Alps Spas; American Spas; Apollo Spas; Aqua Mystic; Aqua …