Pond Algae and What to Do About It

Algae is a normal part of a pond. Rivers and lakes all have algae in them. If algae was absent, this could indicate that there was a problem. However, when there is excessive algae this means that the pond environment is out of balance. Prolific algae is caused by excessive nutrients and to a lesser extent sunlight.

Common causes of algal blooms are:

. leaf fall from overhanging trees

. overcrowding of fish

. overfeeding of fish

. runoff from garden (especially if it contains fertiliser)

. lack of filtration where fish are kept

. nutrient rich potting mixes for aquatic plants

. inadequate water movement

. high pH

. complete water changes

Two types of algae appear in ponds; blanketweed or filamentous algae, or green water or single celled algae.

Some removal options are:

. Remove long strands of algae by hand or with a net.

. Remove sludge layer at bottom of pond. This is often caused by falling leaves etc, and acts as a source of nutrients to algae.

. Use a suitable algae killer. We sell a biological algae control which breaks digests the algae without using chemicals. We also have simazine based products which kill algae directly.

These measures are however temporary, and the problem will return unless preventative measures are taken. Some of these include:

. Installing a filter in the pond and ensure good water movement . Preventing leaves from entering the pond

. Install an edging around the pond to prevent runoff and soil entering the pond following rainfall.

. Plant the pond with suitable aquatic plants to outcompete the algae for nutrients. Water lilies will shade the pond in the warmer months, thereby reducing algal growth.

. Maintain a pond block in the pond continuously