A pond is a stagnant body of water and so unlike a running stream, only the water at the surface will come in contact with the air from which it needs to draw oxygen in order to stay healthy. Without the life giving oxygen in the water, fish will die and algae will thrive. Algae thrive on the un-oxygenated water at the bottom of stagnant ponds and if unchecked will spread to the shallower depths an eventually make a pond unsightly and as the algae have an unpleasant odour, the pond will also become smelly as well as an eyesore. To avoid this happening to their ponds, most people fit an aeration system to their pond. These aeration systems come in several types but care should be taken to ensure that you us an aeration system which is suitable for the depth of your pond. The aeration systems will usually come in two classes, those that are designed for use in ponds with a depth less than 6 feet and those that are specifically designed to be effective in deeper ponds. Of the shallower aeration systems, the fountain is perhaps among one of the most popular and for good reason. Although as effective as any other shallow water aeration system, a fountain can also add a touch of elegance to any pond, making it a thing of beauty with its own distinct character. A fountain will naturally cause a circulation in the water of the pond and that ensures that the water that is thrown up by the fountain keeps changing. As the water is thrown up, it is able to be in contact with the air and thereby receive oxygen, aerating the pond. Another one of the popular pond aerator options for shallower waters is the propeller system. Although instead of throwing water up, the propeller system churns the water, the water is still aerated and the propeller, like the fountain, also creates a circulation within the pond’s water. Deeper ponds are not affected by the circulation created by either a fountain or a propeller aeration system and so for those a diffusion aeration system is needed. A diffusion aeration system is a system that is comprised of three parts, a compressor, a diffusion unit and an air hose long enough to reach between the two once they have been set up. A diffusion system is set up by placing the compressor, which has to be attached to a power source, on the side of the pond and the diffusion unit placed at the bottom of the pond. As air is pushed by the compressor, through the hose to the diffusion unit where it is released, as the air travels to the surface, it reacts with the water on its journey and so therefore allows all the water in the pond, starting from the water at the bottom, to be fully aerated, keeping the pond fresh and healthy. These aeration systems need a power source but some come with their own, perhaps a windmill or a solar kit.