Almost all pond keepers will speak of how rewarding it is to have a pond in their back garden but that their number one annoyance is algae. Common in warmer climates, algae can give the sides of pond liners (or that of a prefabricated or concrete pond) a green, slimy, hair-like coat and even tint the water a dense green. Along with the aesthetic disadvantages, algae can also disrupt the balance of pond water by depleting it of oxygen if left to multiply. But, while algae can give your pond a horrid green-look, it does have an advantage in that it helps your pond appear more natural and provides fish with a healthy food source. Thus, as part of pond maintenance, your goal should not be to eliminate all algae. Instead, it should be to manage its growth to keep the population at a desirable level. Knowing what factors contribute to algae growth, will help you keep a healthy, well-balanced pond.
One factor encouraging algae growth is a dramatic increase in sunshine, which most UK pond owners will be experiencing this summer. A second factor is the nutrient content of water. In a natural setting, fish produce nutrients that are absorbed by plants, leaving very little for algae. However, many garden ponds do not have enough plants growing in them to handle all the nutrients produced by the fish. This causes an excess build-up and produces an ideal environment for algae growth. Whether you are in the process of constructing your pond and want to avoid algae problems once your pond is established or have an existing problem to control, you’ll first want to increase the number of oxygenating plants on the surface of the pond. This is the simplest solution to keeping water clean and clear. You can also reduce direct sunlight into your pond by adding floating plants, such as lilies and lotus, whose leaves provide shade to control algae growth. Add submerged plants that release oxygen to the water. All aquatic plants absorb nutrients and starve the algae. Marginal plants, planted around the periphery of the pond or in the shallow sections of the pond, are also effective in absorbing nutrients and providing some shade.
A further step to reducing the nutrient content in the water, is to make sure you feed your fish only enough food that they will consume within five minutes and to feed them quality fish food, as it will be fully digested, leaving fewer nutrients to pass through the fish into the water.
Don’t be discouraged by algae as the problem is often easily solved if corrective steps are taken.