Pond Algae Control

pond cleaner and removal of algae

Algae is essential to a healthy pond.

However, excessive growth of algae and discoloration of the water may mean that the water quality of the pond is poor. Too much algae can impair the aesthetics of your backyard pond and could potentially harm your fish and aquatic life.

There are a few good options for preventative care of an algae bloom, but how can you control algae in your pond naturally? And how do you control algae once it has become a problem?

Remember: Algae control starts with algae prevention.

An algae “bloom” is an accelerated and uncontrolled growth of algae in your pond. For most pond owners, algae blooms are one of the first visual signs of an algae problem. The most common reason why ponds have excessive algae growth is from excessive nutrients in the water supply. When combined with sunlight, carbon dioxide, and warm temperatures, algae can easily grow out of control.

Maintaining proper nutrient levels are key to warding off algae, and natural occurrences like excess rain water can be detrimental to the health of your ecosystem. Learn the effects of rain on your pond.

While trying to restrict nutrients from entering your pond is important for success, it is not always enough. In this article we will review your options of how to control and remove this nuisance in your pond that causes foul odors, fish death, and a less than visually appealing nature which can lead to new pond syndrome or green water.


The most common method of algae control is to add a copper based algaecide to kill the visible algae. Algaecide may be useful from time to time, but need to be applied with care. Overuse and/or killing algae off too quickly can come with its own set of problems, including oxygen depletion in the pond and toxic reactions for fish, native plants, and wildlife.

Koi Pond Care In The Summer Tip: Keep in mind that during the hotter months, your pond water will evaporate at a much higher rate. The lowered volume of water in your pond makes for a smaller physical ecosystem and contributes to one of the leading causes of Koi loss

Many algaecides also negatively affect the “good” bacteria designed to help keep a pond cleaner. Once these are wiped out, algae can grow more readily and may force a pond owner into a never-ending cycle of chemical use. Algaecides can be effective at controlling what you can see, but this does not address the bigger problem. Killing the algae can also contribute to more and more excess organic matter as when it dies. As a result, the algae problem will come back time and again. Start the season right with with our pond opening tips for the spring.

Leftover Decomposing Algae

Breaking down some of that excess organic matter is critical to controlling algae long term. Many ponds have from 3 to 24 inches of organic matter resting on the bottom. This organic matter releases excess nutrients as it decomposes and more so if the pond has a shortage of oxygen in its deeper parts.

A more radical solution to removing the excessive organic matter is dredging or even draining the pond, cleaning out the bottom and starting over. This can definitely work, but is very expensive. Also, once you clean out the pond, the problems can start all over again unless you take a proactive approach to managing excessive organic matter.

Adding Aeration

Adding aeration and circulation in your pond is the most important thing you can do to help prevent algae long term. Aeration increases the level of dissolved oxygen in the bottom part of the pond which increases the number of aerobic bacteria. These bacteria, in turn, begin to feed on the excess organic matter and reduce the amount of nutrients released.

Adding Beneficial Bacteria

Beneficial bacteria work at decomposing excess organic matter, sticks, leaves, decayed fish and excess nutrients. They don’t have to be combined with aeration, but adding oxygen will significantly increase both their numbers and their level of activity at the bottom of your pond where you need them most.


Another commonly used option for algae control is manually scraping with a rake or weed eradicator. These options are not for everyone and can require considerable time and effort to be effective. Grass carp sometimes eat algae, but it is not common. They have been seen eating plants coated with algae, but their mouth and gills are not positioned to eat algae effectively. Although grass carp can be used to control some aquatic weeds, they should not be stocked to control algae. In fact, grass carp can add to a nutrient problem and cause algae to multiply if they are no longer eating aquatic weeds efficiently.

Controlling nuisance algae is vital to the health of your pond. Balancing out your pond naturally will lead to better long term results than quick fixes. Do your product research and learn what solution or combination will best benefit your fish, plants, and overall pond health.

Thinking of buying a UV light? Learn more about the pros and cons of a UV filter for your pond.


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