Creating a Balanced Garden Pond

The ideal garden pond is one that has a natural and harmonious balance. This can rarely be achieved where the reflective quality of the water is its paramount attraction, or where major moving water features play. However, in the traditional well-planted garden pond with its modest complement of fish, it is a realistic and long-lasting proposition. It is essential that every component involved achieves harmony from the beginning.

When looking at the principles of natural balance it is clear that there are two important aspects that require immediate consideration - the provision of abundant underwater growth and surface shade. Submerged plants perform an invaluable and often diverse role. Their main task is to mop up nutrients in the water and to release oxygen during the day to sustain fish and other aquatic life. They are also to some extent a food source for fish and often serve as a nursery for fish fry. So they clearly have a major impact upon a pond's ecosystem. By removing excess nutrients from the water, submerged aquatics deprive green water-discoloring algae of the opportunity of becoming established.

Green water can also be controlled by the amount of light that is permitted to fall into the pond. Algae, like most other aquatic plants, must have full uninterrupted sunlight in order to prosper. However, planting trees and shrubs to shade the pond is ill-advised as this will prevent the desirable plants like waterlilies and marginal aquatics from growing properly and will have an adverse effect upon their floral display.

The solution is to provide shade on the surface of the water by means of floating plants and waterlily pads. These should not cover the entire pond, for cutting out the light completely beneath the water will cause the submerged plants to perish. No more than one third of the surface area of open water should be covered with foliage if green suspended algae is to be controlled successfully and the submerged aquatics permitted to continue in healthy growth.

Ornamental fish also make an important contribution to the balance of a pond. They are invaluable for keeping pests under control, not only those that attack the plants, but also mosquito larvae, which if left unchecked pose potential discomfort for the gardener. The waste matter that fish produce is also of benefit to the plants. Snails can also make a contribution, for if suitable species are selected, they will graze upon filamentous algae, which is largely unaffected by the competition created by the submerged aquatics.

When establishing a pond there is a formula that can be used to provide a general guide for planting. In assessing the area to be shaded by foliage and occupied by submerged plants, calculate the surface area of the pond excluding the marginal shelves. This is the area that should be covered for approximately one third with floating foliage.

When calculating the number of submerged aquatics required, allow one bunch of cuttings for every square foot of surface area. That is not to say that the plants must be distributed over the pond floor evenly in such a ratio, it is the specific number required for the given surface area. With fish a maximum stocking of 6ins of length (including tail) to every square foot of surface area, although initially 2ins to the same surface area is sensible. Water snails of suitable species can be introduced freely.