Suitable for fresh water and sea water tank 3.More than 10 times the abilityto cultvate nitrifying bateria than normal bacteria house 4.Wash it with aquarium water before use, do not use tap or boiled water 5.Do not often change these rings. 6. After six month used, change half of them and use new rings with the rest old rings 6.Ceramic Ring is an essential filter media for every aquarium. 7.It can effectively eliminate odours, detoxifies harmful metals, purifies and soften the water absorb chemical residue/ compounds and water purifying effect. 8.Ceramic Ring is frequently recommended for use in aquarium filters. 9.Using this in your filter system, naturally good bacteria will create in your fish tank. 10.You can keep this in all the places where the water circulates in your filter system for your tank.