In the natural world ponds are large enough and their inhabitants varied enough to achieve balance on their own, where animal waste is metabolized by bacteria, bacterial byproducts are consumed by plants and plants are eaten by animals. The best way to achieve balance in the garden pond is to emulate nature.
How to Clear Pond Water Naturally?
Achieving clear pond water naturally means that its contents are in healthy proportions. Pond plants are important when it comes to a clean pond, and it is practical to keep water ammonia levels and nitrate content in check.
The addition of abundant plant material can only help to clear and clean pond water, enhancing the health of the system by removing excessive nutrients and contaminants and adding color and charm, even daytime oxygen, on the way. Plants are of course necessary in any pond where people aren’t adding food, as the only source of nutrition, but they are even more critical when there’s an abundance of fish food in the system (as there usually is, in excess, wherever Koi are found). That’s because of what the Koi do to the food… Yes, they do that too, but it’s the excretion of ammonia that really fouls the nest.
Now, although plants can and do metabolize some ammonia directly, it’s the Nitrogen Cycle, involving several types of bacteria before the plants come back into the picture, that’s really important to understand. Ammonia excreted by fish is toxic to them in concentrations of as little as one part per million! Certain bacteria are able to metabolize ammonia extremely efficiently where there’s plentiful oxygen, leaving still-toxic nitrites as their byproduct.
Other bacteria process nitrite and oxygen and produce relatively harmless nitrates. Here’s where the plants come in. Nitrates are plant food, and the more fish food you put in at one end of the system, the more plant food floods the water. If there aren’t enough ornamental plants to consume the nitrates, algae are always waiting in the wings, both free-floating (‘green water’) and string algae, to bloom prodigiously. So as long as the fish food goes in, the plant food is there… what would you rather grow, waterlilies and irises, or green slime?