Biological Concepts & Ecological Balance In A Garden Pond

It really is necessary to get a grasp of the whole concept of ecological balance for the more intelligent maintenance of your pond. This, of course, involves the clarity of the water and the health of your fish and plants.

In the course of formation of a natural pond, the plants, fish, insects and minutiae develop and interact over a long period of time. The water achieves a balance or equilibrium whereby no plant or animal predominates and if they do proliferate, they are controlled naturally by predators or other environmental conditions.

To achieve this balance is the aim of every potential water gardener. Because we are often combining all the ingredients planting and stocking the pond all in the space of 10 days or less this is not always possible without some serious thought.

Consider a hypothetical pond built over a weekend. The pond is filled with tap water and then left to stand. As soon as the chlorine in the water has dissipated the water starts turning green due to the growth of minute unicellular free-floating algae. As it progresses things gets worse and worse until it resembles a thick green pea soup.

Begin again by emptying out the green water, but this time adding oxygen plants bog aquatics and water lilies in the following formula.

To each sq./m (about 10 sq. feet) surface area of your pond you should have:

• 2 bunches of oxygenating plant

• 1 water lily or surface covering plant

• 12 water snails

• 1 aquatic bog plant

These need not, of course, be spaced out metre by metre combining for instance 3 or 4 bog plants together in one corner as a design feature.

Algae grow and flourish in the presence of sunlight while absorbing nutrients from the water. By planting water lilies we provide coverage and shelter for many algae eating animals and insects, we block the penetration of sunlight and hence keep the water cooler.

Oxygen plants compete for nutrients while at the same time releasing oxygen into the water on bright, sunny days.

Bog plants serve a similar function in their growing process, consuming nitrates which have been produced by bacterial action.

All the above is vastly simplified but the general effect is over a period of 3 to 5 weeks the pond gradually clears and stays clear while this balance is maintained. The water assumes a greenish tinge and slightly cloudy which is a normal condition. as the pond progresses and the plants take hold, many insects such as dragonflies, mayflies and various aquatic species, will take up residence.

Minute water fleas (daphnia) appear and even frogs and toads with their inevitable progeny.

All these play their part in the water garden scene and all are necessary.

With the advent of spring the pond very often starts going green due, of course, to the algae getting off to an early start. At this time the blanket weed or filamentous type algae appears. These can become a pest but generally are only associated with crystal clear water. Remove them physically or using a notched stick and by full summer you should have no more trouble.

To maintain the carefully achieved balance in your pond constant attention is needed .. therefore remove

• all fallen leaves

• debris

• dead animals (fish)

• or yellowing aquatic foliage.

These, if left, simply decay and add nutrient to the water, thus stimulating algae growth. Do not allow water lilies, floating plants or bog plants to shade more than 2/3 of the pond. The fish need open water and the critical oxygen balance of the water could be impaired by over coverage.

Control the oxygen grasses again limiting to about 1/3 coverage.