null

Skip to Main Content

Why Does Algae Grow in Ponds?

Why Does Algae Grow in Ponds?

Asked by: Doug from Lawrence, KS

A: Algae are tiny aquatic plant-like organisms or protists that grow via photosynthesis. Ponds provide them with four vital components they need to thrive: nutrients, carbon dioxide, water, and sunlight. Keep reading to learn how pond algae grow, and then check out our top recommended pond and lake algae control remedies to eliminate blooms in your pond.

Nutrients

Algae require minerals to grow and reproduce, particularly nitrogen and phosphorus. Both elements enter a pond through decaying organic debris, animal waste, and storm runoff. Reduce available nutrients in the water by adding beneficial nitrifying bacteria and aquatic plants like lilies and cattails.

Carbon Dioxide

Decaying organics release carbon dioxide into the water column, which often gets trapped due to thermal stratification. This can create dead zones where the CO2 levels are too high and the oxygen too low to support fish and other aquatic animals. Algae and some weeds thrive in these conditions.

Stagnant Water

Algae flourish in still or slow-moving water like ponds, swamps, and marshes. Natural movement from streams and springs or supplemental aeration systems disrupts growth. Aeration also releases trapped carbon dioxide while boosting dissolved oxygen levels, eliminating the previously mentioned dead zones.

Excessive Sunlight

Algae need ample sun exposure to grow. Ponds in full sun with little or no shade can become hosts to uncontrollable algal blooms. Add floating pond plants and fish-safe pond dye to provide shade and hinder algae growth in your pond.

All Your Algae Questions Answered

Do you have more questions about pond algae? Check out the helpful guides below, or contact us at 866-POND-HELP today!

What is Algae?

Types of Algae in a Water Garden

Control, Remove, and Prevent Algae Blooms

Is Blue-Green Algae Toxic?

Last Updated: February 4, 2025