A pond can be a beautiful and ornamental addition to a garden or home, but it might lose some of its charm if the water is green and murky with algae. Especially in warmer climates algae bloom occurs more and more often in the last years. Therefore, it is important to understand what is causing the algae bloom prior to eliminating it.

Most algae blooms require three factors to bloom: Sunlight, carbon dioxide and nutrients. As other plants, algae use sunlight and carbon dioxide for photosynthetic processes to produce energy and to initiate further growth under consumption of nutrients. Most common nutrients are nitrogen or phosphorus that enter the pond trough fish excrements, dying plants or human impacts such as fertilization.

Too much algae bloom endangers the overall health of a pond as it prevents sunlight from reaching plants underneath the water surface. Consequently, photosynthetic processes stop so that these plants die and provide additional nutrients for more algae bloom. Even worse, without aquatic plants the oxygen level in the pond decreases more and more until fish suffocates and dies as well. Dying sea life provides again more nutrients for enhanced algae growth. More and more algae bloom also prevents oxygen from entering the pond on the water surface until the pond completely turns over.

Chemicals or manual removal of algae provide only a short-term solution until the algae comes back as they don’t eliminate one of three factors for algae growth. Chemicals will also kill other aquatic plants which provides nutrients for new algae growth. Manual removal leaves algae spores behind in the water that will soon cause new algae blooms.

As we cant really influence how much the sun is shining or much carbon dioxide is in the air the only solution to remove algae permanently is to reduce nitrogen and phosphorus levels in the pond. As in a wastewater treatment plant every pond contains certain types of bacteria called Nitrobacter and Nitrosomonas that consume nitrogen. Increasing their number results in reduced nutrient levels for algae bloom which consequently eliminates the algae.

Other than nitrogen the bacteria need oxygen for enhanced growth. To increase the oxygen level in the pond an aeration diffuser system – as supplied by AET – has to be installed.

An aeration diffuser supplies oxygen to the pond trough a fine bubble membrane. As smaller the bubbles are as better is the oxygen transfer rate so as more oxygen can be dissolved in the water. At the same time a proper designed aeration diffuser system ensures a good water mixing so that the bacteria colonies can easily spread out in the whole pond. The bacteria itself is harmless for humans or sealife and will reduce its number automatically when the nutrient levels of the pond decrease.