A backyard pond is a small, human-constructed environment. As such, it needs humans to help manage its ecology and correct gardening problems that cause imbalances in the ecosystem. Poor pond water quality is a problem that can hurt fish populations, reduce the numbers of good invertebrates that live in a pond, and ultimately damage plants. If you have an overabundance of nutrients and sediment in your pond, you need to find the source and remedy the problem so that pond animals and plants stay healthy.
Too Many Nutrients In the Pond? Fish Might Be the Cause
Pond lovers often love fish, but if you get overzealous, fish feces and fish food can cause nutrient problems in the pond. High levels of nitrogen and ammonia can lead to the death of prized fish. A rule of thumb is to allow 24 inches of pond surface per inch of fish. Remember that fish will grow, so determine how big they will get and use that measurement.
Fall Leaves and Pond Nutrient Levels
In the fall, leaves from deciduous plants fall into the pond. These look attractive, and a few leaves here and there will not damage the pond. However, if the pond is small, has many fish, and does not have good filtration methods in place, extra leaf matter can push nutrient levels over the edge. Skimming leaves with a hand skimmer or adding netting over the pond in the fall if the pond is under a tree are two ways to manage the inflow of plant material.
Fertilizers Can Drain Into the Pond
Gardening practices can also lead to nutrient problems. In the areas around the pond, gardeners may place fertilizers on the plants. If the fertilizers are fast-release, then they can move out of the soil quickly. If garden design moves water from the gardens into the pond, then the pond will receive part of the fertilizer. Adjusting gardening practices and moving toward natural and slow release fertilizers helps manage nutrient inflow into the pond.
Too Much Sediment In the Pond
In a hard-bottomed pond that has a plastic or concrete shell, sediment comes from the landscape around the pond. If the water in the pond is muddy, take a good look at the areas around the pond. Pathways in particular are sources of sediment. As people walk on the pathways, they move soil and gravel around, and in rain and wind the loose soil makes its way to the pond.
Landscape Design Around the Pond Reduces Sediment Problems
Good landscape design helps reduce sediment problems. Create a buffer of low-growing plants around the pond. These plants will pre-filter the water that moves into the pond from the surrounding landscape. When you are planning the pond or redesigning parts of the garden, place the pond in an area where the water will drain away from the pond. Position landscape tiles and pathways on a slight angle so that the water runs off into other areas of the garden.
The Role of the Pond Filter
Ponds need filtration. A mechanical pond filter helps take out some of the sediment in the pond. Plant-based filters also work to remove excessive nutrients. Some marsh reeds and irises are used specifically to filter nutrient-rich water.
A well-balanced pond is a healthy pond. By adding appropriate filters and small numbers of fish and by adjusting garden designs and practices, you can keep your pond healthy.
Tricia Edgar - Tricia Edgar is a gardener, environmental educator, and science writer from the Pacific Northwest.
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