Aquarium II - 7 Stage RO/DI Water Filtration System (100 GPD) Provides 0ppm water using 7 stages of water purification for the purest water. Production capacity of up to 100 gallons per day. 3 Stages of DI resin to ensure only the purest water reaches your aquarium. Perfect for both fresh and saltwater aquariums. No more need to purchase chemicals or carry home water from your local fish store.