3 Stage Compact RO System for Aquarium 100 GPDUSAGE: Aquariums tropical fish, marine, Reverse Osmosis water production DESCRIPTION: Compact 3 stage reverse Osmosis system removes 97. 8% of all known contaminants. Gives you clean RO water when required for fish tank. Connect from cold water supply or garden tap into your aquarium or other. (3 4" to 1 4" garden tap fitting OR 1 2" to 1 2" fitting OR copper pipe self piercing valve all available but the 3 4" to 1 4" sent as standard others on