Removes Ammonia within hours and Nitrites a little longer. Every good Koi keeper needs this product on your shelf for that rainy day when the filter crashes out. For whatever reason the ammonia level goes out through the roof, there is a set course of actions to undertake, but the very first action is to load out with ZX8 to give you extra time to sort out what went wrong with your system. There is no escaping the out come. ZX8 will save your bacon.