We offer a complete selection of reverse osmosis systems for your Aquarium or Reef System Reverse Osmosis is the most popular and cost effective method to purify aquarium water. An RO system removes virtually 99% of contaminants in water including bacteria pesticides fluoride and other dissolved ions. A system comes complete with prefiltration reverse osmosis storage and a faucet. Adding a deionizer will give you 100% ionic purity. These system can also provide you with great drinking water.