Siso Water Crystal It can completely get rid of ammonia nitrogen and heavy metals such as nitrite, so the water becomes fresh It works to filter murky water with fish waste and unconsumed food remains It is not necessary to change the water for a very long time if you use Crystal Water every week Hydrocrystalline crystals have the ability to increase the decomposition rate of ammonia by 200%, so that the rate of decomposition of waste becomes faster. Crystal is essential for your aquarium water to remain clear for a long time