What is algae? Algae (sing. alga) are simple organisms that derive energy from the sun by carrying out photosynthesis. The higher land living plants are believed to have originated from algae and they are quite similar to each other. You will however find a series of distinct organs in higher plants that can not be found in algae. Algae can be unicellular as well as multicellular and some types form large and complex forms. The “seaweeds” that you can encounter in the ocean are for instance algae; not aquatic higher plants.
Algae are an important part of the ecosystems where they occur, but they can also become a nuisance for aquarists, pond keepers and swimming pool owners. In order to successfully combat algae it is important to understand what algae are and how they subsist. Just like a land living plant, algae need light, water, nutrients, carbon dioxide and oxygen. Oxygen is produced as a bi-product of photosynthesis and getting enough carbon dioxide and water is rarely a problem in aquariums, ponds and swimming pools. The main limiting factors are therefore light and nutrients. By controlling the amounts of light and nutrients, we can carry out successful algae control in ponds, aquariums and swimming pools.
Pond algae control
Many different methods can be used to combat pond algae and the bests results are normally achieved by combining several different methods. As mentioned above, limiting the amount of light and nutrients will make the habitat less suitable for algae. You can also introduce algae eating organisms to your pond and/or use some type of algaecide. Before you decide to use an algaecide for pond algae control, you should keep in mind that algae mass-death can have a devastating effect on water quality and make the oxygen levels of the pond decrease sharply. This can in turn harm or even kill fishes and other aquatic organisms in the pond. Algaecides are a short-term solution; unless you combine it with other actions you will never achieve a stable pond with suitable amounts of algae growth.
Limiting the amounts of nutrients that reaches the pool is usually easier than limiting the light. If you are planning to dig a new pond for your garden you can however take light into account and chose a shaded part of your garden where pond algae is less likely to thrive. (But don’t forget that placing your garden pond next to trees and bushes will force you to clean your pond more frequently since leaves and other types of debris will fall into the water.)
Two major contributors of nutrients to a garden pond are food and surface water. If you keep pond fish or any other animals in the pond, make sure not to over-feed them. It can be a good idea to introduce scavenging species that will seek out left-over food and devour it. After heavy rains, surface water streams that empty themselves in the pond tend to bring large amounts of nutrients to the water. You can prevent this by building a mound around your garden pond or dig special trenches for surface water. It is also a good idea to avoid using fertilizers (especially those rich in phosphorus) in the area around the garden pond.
You can force the algae to compete for nutrients by keeping your garden pond heavily planted. If you have plant eating fish or other animals in the pond, chose though and sturdy plants that grows fast and will tolerate being nibbled on. In a pond filled with plenty of thriving plants, there will be much less nutrients available for the algae and this will limit their growth rate and make sudden algae blooms less likely. There are many different pond plants to choose among; make sure that you pick species that will thrive in your particular climate and avoid delicate species that might find it hard to compete with the algae.
Aquarium algae control
Just as in a pond or swimming pool, the one who controls light and nutrients will control the algae growth of the aquarium. Controlling how much light that reaches an outdoor swimming pool or pond is naturally tricky, but controlling how much light that reaches an aquarium as fairly straight forward. One of the reasons why so many aquarists chose to place their aquariums in basements and garages is that such areas typically have small windows or no windows at all. It is also easier to make the rest of your family accept a darkened room in the basement than a darkened living room or kitchen. Use a timer to control when the light is switched on an off each day.
When it comes to nutrients, it is very important not to over-feed your fishes since left over food can become food for the algae and cause an algae explosion in the aquarium. Keeping the water quality up is not only important for the well being of your fishes; it is important if you wish to keep algae growth under control as well. Do not feed your fish more food than what they will devour in a few minutes. Ideally get a “cleaning crew” of suitable scavenging species that will seek out left over food and eat it. It is also important to carry out frequent water changes since this will remove nutrients from the water.
Last but not least, you can use animals and plants to combat algae in the aquarium. Plants and algae compete for the same nutrients and algae problems are therefore less common in well planted aquariums. Use can also introduce animals that will feast on algae, such as algae eating fish and invertebrates. It is important to choose animals that will appreciate the environment (pH-value, temperature, tank mates, etcetera) in your particular aquarium. Also keep in mind that many algae eaters need to be given food as well since they can not get everything they need by grazing the limited amounts of algae present in your aquarium, especially not after a while when they have decimated the algae populations.
Other algea articlesAlgae eating fish - An article about differen algae eating fish.
Siamese algae eater - Information on this popular algae eater.
Central American Cichlids
Frogs and Turtles
Lake Victoria Cichlids
Marine Aquarium Fish
Responsible Fish Keeping
South American Cichlids
Tropical Fish Food