Fish eat food and create waste. Debris falls into the pond and
decomposes. In decorative ponds, a “closed system” generally refers to a man made membrane liner placed in the excavation. Ideally, bottom filter intake systems, drains are employed to actively remove organic solid waste on an ongoing basis. |
These dissolved waste products, primarily
ammonia , meet nitrifying bacteria in the biofilter
and are digested, creating their own waste products. |
This waste product is then digested by a secondary bacteria and
in turn they produce a waste product: nitrates
.
Nitrates are far less toxic to the fish population than the
original ammonia waste product. Water changes are needed at regular time intervals for ridding the closed system of end waste products of biological filtration, primarily nitrates.
Filter sizing varies depending on species of pond inhabitants, population sizes, pond profile shape designs, type of filter and media used.
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In the natural world,
a myriad of other bacteria and countless other microbes would
digest this nitrate waste product and therefore consume this
nitrogenous waste. Plants, also use nitrates as a nutrient source. |
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In a closed system, such
as a fish pond the most typical method of removing this final
waste product is by doing 20% water changes each month. (This
20% water change water is great for your garden or house plants
as it is rich in nitrates, a basic plant nutrient.) |