What is Pond Algae?

How to Get Rid of Algae in a Large Pond

We all know that the right kind of algae is beneficial to most aquatic systems; but left unmanaged, it can wreak all sorts of havoc. Large blooms release toxins that are harmful to fish, humans, and other animals that might drink from the water. They’re also responsible for a high percentage of fish kills. 

That’s why we’re going to outline how to get rid of algae in a large pond. 

But first, let’s review the most common, different types of algae you’ll find in large ponds:

Planktonic Algae: The word plankton is derived from a Greek adjective meaning errant, and also, wanderer or drifter. They are found in ponds, slow-moving rivers, lakes, and the ocean. 

Planktonic algae don’t have a root system, but these microscopic plants are suspended in the water and can rapidly turn the water into different shades of green and brown. These microscopic plants bloom if they get excessive nutrients, like phosphorus and nitrogen. And, of course, sunlight.


Though they shade the pond’s bottom, deterring the growth of unwanted plants from growing beneath the surface, they also can deplete the oxygen in the pond, thus endangering fish. If oxygen becomes severely depleted, a “fish kill” could occur.

Filamentous Algae: Filamentous algae, also known as string algae or pond scum,  is also microscopic but gets “stringy” as it mats together and floats on the surface. If a pond gets too covered by string algae, fish kills are more likely, and the rotten egg smell can develop as the pond becomes stagnant. In addition, more muck is going to develop at the bottom of the pond, increasing the likelihood of eventual dredging.

The Use of Algaecides

Algaecides are generally used to get rid of algae in a pond — or even mollusks and fish pathogens in canals and other bodies of water. There are several kinds of safe algaecides you can find online, but it is best to determine first which kind of algae you are trying to treat, and then we heartily recommend you follow the instructions so as not to threaten any animal life.


How to Prevent Algae

The best way to get rid of algae in a pond is prevention. This is done by significantly reducing the nutrients that seep into your pond from fertilizers, animal waste, or urban runoff.

Make sure not to apply fertilizers on slopes, and keep yard clippings or leaves away from your pond. You can grow plants at the shoreline to absorb the runoff of nutrients. Adding pond dye can also reduce algae growth by blocking sunlight. 

Also, consider pond aeration. If your pond is less than seven feet in average depth, surface pond aeration is fine, but if it is deeper, you should consider purchasing a bottom diffuser unit.

The Difference Between Bottom and Surface Aeration

Proper aeration is one of the most trusted and best ways to get rid of algae in a pond. Most people want a display, and in that case, a pond fountain, either a display fountain or an aerating fountain, is used. Three parts are needed: 

  1. A float
  2. A pump attached underneath the float
  3. A nozzle on top of the float 

But, if your pond is deeper than seven feet, you will need to use bottom aeration. Three parts are combined for bottom aeration as well: 

  1. An air compressor
  2. A diffuser
  3. Tubing that connects the air compressor to the diffuser.

The tubing should be weighted enough that it sinks to the floor of your pond. The compressor needs to be housed to prevent burnout or shorts due to bad weather. Since all the action occurs below the surface, there is no display.

  A display fountain (multiple displays)

aerating fountain Aerating fountain (V-display only)

  A bottom diffuser in action

Algae Prevention with Fountain Mountain

And that’s how to get rid of algae in a large pod! If you’re looking for simple, effective ways to keep your pond properly balanced while looking and smelling great, we recommend you check out our pond fountains.


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