FROG Maintain for Swim Spas - Non-Chlorine Shock for Use With @Ease Floating System - Single Dose Packets for Easy Spa Maintenance & Treatment - 2 PackBrand: FROG Features: Non Chlorine Shock: Shock your swim spa once a month with FROG Maintain for Swim Spas, the recommended non chlorine shock cleaner that pairs with the FROG @ease Sanitizing System for Swim Spas; single dose works for swim spas up to 3,000 gallons Effective Water Maintenance: Add FROG Maintain about 3 weeks after putting the FROG @ease for Swim Spas System to work; FROG Maintain will give the SmartChlor Cartridge about 1 more week