The term “algae” refers to a varied group of plantlike organisms with simple biological structure. Algae are present in lakes and other bodies of water, and as part of a balanced aquatic ecology, they’re not harmful. Under certain conditions, however, algae may grow so quickly that they threaten a pond’s health and usefulness.
Algal Bloom
Excessive algae growth is referred to as an algal bloom. An overgrowth of algae lessens the recreational and aesthetic value of a river, as well as the pond water may become poisonous if certain kinds of blue-green algae are present. Algal blooms even threaten other river organisms, such as fish, because as large amounts of algae die and decompose, the amount of dissolved oxygen from the water decreases.
Pond Characteristics
Some ponds are more susceptible to excessive algae growth. Like plants, algae are usually photosynthetic, meaning that they use energy from sunlight to produce their own food. Consequently, shallow slopes are prone to algae issues due to more sunlight penetrates into the shallow water. Shallow water also tends to be somewhat warmer, and this favors algae growth. Stagnant ponds are debatable, because water movement discourages algae growth.
Nutrient Levels
Algae thrive in environments that are full of potassium and nitrogen. Under natural conditions, algae growth is limited because these two nutrients are usually in limited supply. But when runoff carries excess nitrogen and phosphorus into a pond, or when heavy rainfall causes extra runoff, an algal bloom gets possible. Typical sources of potassium and nitrogen in runoff are agricultural and agricultural fertilizers. Soil erosion may also lead to algae growth, since potassium is bound in soil particles.
Prevention Tips
Certain aspects that promote algae growth — such as warm weather and excessive rainfall — are unavoidable. However, a couple of simple techniques can allow you to cut or prevent algae issues. Don’t apply excessive amount of fertilizer; also, if needed, adjust your drainage pathway to direct agricultural runoff away from your pond. You should also maintain and encourage vegetation along river banks; the vegetation can help you to filter runoff and control soil erosion. An aerator, which is a system that increases the oxygen level in a pond, discourages algae growth and reduces the amount of available phosphorus in your pond water.