In all ponds with fish, it is vitally important to install pressure filters with UV Clarifiers. This set up acts like a mini sewage treatment system and accelerate the nitrogen cycle for your pond.
The full cycle takes approximately 4-6 weeks to fully mature (dependent on size of pond and weather) with continuous 24hr circulation.
It is critical to ensure the pump is not turned off as the good bacteria will die quickly and the cycle will be broken. Briefly, the cycle is as follows;
1. Fish waste & rotting plant matter turns to toxic Ammonia
2. Beneficial bacteria living inside bio medias (in filters) converts the harmful ammonia into nitrite
3. A different type of beneficial bacteria further converts nitrite into nitrate
4. Plants can then use the nitrate as food source.
See diagram below showing typical cycle.