Why Does Algae Grow in Ponds? (And How to Stop It)

Algae growth is triggered by an overabundance of nutrients, particularly nitrogen and phosphorus, in water. Algae require sunlight to photosynthesize and grow, which is why blooms are more common during warmer and sunnier months.

But where are all of those nutrients coming from?

Common Causes of Algae in Ponds:

• Lawn and garden fertilizer runoff 

If you fertilize your lawn or nearby flower beds, rain can wash those excess nutrients into your pond. Also, some soils and sands are naturally higher in phosphates, requiring more pond upkeep.

• Agricultural Run-Off 

Water flowing across agricultural land can contain excess nutrients, herbicides, organic matter and sediment. All of these can have a negative effect on the aquatic environment, fueling algae.

• Pet and wildlife waste

Fish poop, bird droppings, or even your dogs backyard business can all spike nutrient levels.

• Decomposing organic debris

Think of leaves, grass clippings, or dead plants that fall in and rot, basically turning into a compost pile in your water.

When run-off enters the water, it is essentially the same as pouring in Miracle-Gro. Over time, this leads to thick algae blooms that can choke out oxygen, harm fish, and turn your pond into a murky mess.

How to Get Rid of Algae (and Keep It Gone):

The good news is that algae is easier to prevent than to treat, and we have science-based tools to help.

• ProClear Algaecide

NSF-60 certified and safe for fish when used as directed. It clears algae fast and improves water clarity.

• Aeration

By keeping water moving, you make it hard for algae to settle and grow. It also breaks down nutrients, such as phosphates, that algae feed on.

• NaturalClear Pond Bacteria

These beneficial microbes consume the same nutrients that algae rely on, starving the algae. We also sell NaturalClear Pond Plus, Lake, and Lake Plus.

• QuikClear

Reduces phosphates fast! QuikClear also efficiently clarifies water that has turned murky due to suspended particles.

• Pond Dye

Acts like sunglasses for your pond. It blocks sunlight from the bottom, making it harder for algae to photosynthesize.

Controlling algae isn’t just about a pretty view, it’s about maintaining a healthy, balanced pond ecosystem. Whether you’re managing a backyard koi pond or a large farm reservoir, staying ahead of algae means using the right tools against it and understanding the science behind it.

We’ve got you covered for solutions that work with your pond’s biology. Any questions? Email sales@pondpro.ca to speak with one of our experts!