How to Get Rid of Algae in Your Pond - Backyard Boss
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How to Get Rid of Algae in Your Pond

That slime blanket on your pond has taken over and you don’t know what to do. Call in the professionals? Abandon the water to the creatures beneath? Or you could use these tips and tricks for pond algae control. Be sure you’re ready to do some work though if you’re going to do it on your own. It will take a little time, some patience, and a little investment in beneficial products, plants, algae-eating fish, and more. But don’t worry, it’s not too hard.

So What’s the Big Deal About Algae Anyway?

Besides being unattractive in many cases, algae can have some negative impact on the life in your pond, whether you’ve stocked fish, snails, frogs, or just let nature take over and stock the pond with wildlife on its own.

Algae hinders plant growth, keeping those lovely water lilies and irises from growing as healthy as they should, while also being toxic to fish in many cases. The type of algae will determine which is dangerous and which is just ugly, but overall algae isn’t a good thing to have around.

What Causes Algae Outbreaks?

frog floating in algae green water

So what causes algae, you might ask. It’s both simple and complex at once. The simple explanation is that the water contains an excess of nutrients that the fish, plants, and other living things cannot consume. Algae particles are pretty much always present in the water, and because algae require very little caring either for pH or clarity, it grows quickly when nutrients become available.

High pH and phosphorous levels are typically what causes algae to bloom. Things that typically create these issues include :

  • The introduction of foreign materials (like granite, limestone or untreated concrete).
  • Overstocking of fish.
  • Excessive plant growth.
  • Fertilizers that leaked into the pond.
  • Iron.
  • Grass clippings entering the pond.

How to Deal with Algae Without Harming Your Fish

Initially, there are a few things you can do to deal with the algae.

  1. Physically remove the algae from the pond. Scoop it out with buckets, nets, your hands – whatever you can use to get rid of it from the pond. I’ve often used a pool skimmer for the job. For larger ponds, I’d recommend a parachute skimmer.
  2. Remove decaying plants and detritus.
  3. Use treatments like chemicals or all-natural products.
  4. Add in some algae-eating fish.
  5. Add in some algae-deterring plants.
  6. Avoid over-feeding your fish to eliminate some of the waste.
  7. Find the cause of the algae and treat that specifically.

    Parachute skimmer

fabric skimmer on pond with algae outbreak
    Pond skimmer for algae, duckweed, and more for large ponds

Algae Eating Fish

koi fish swimming in clear pond

In addition to whatever fish you may already have stocked in your pond, there are a variety of species of pond fish who love to nosh on algae for their dinners. There’s special care needed to determine if your pond is a good place for them though, so be sure to check their pH, water temperature, and other needs before just going out and buying a bunch of koi and expecting miracles.

Be sure to study up on which species of algae eaters get along with the fish you’ve already got stocked in your pond. They’re definitely not a one-size-fits-all kind of thing. Some species are more aggressive for example, and will attack fish you may already have on hand. Others could become dinnertime for species you’ve already got stocked in.

I will note, you’ll get rid of some of the algae with these swimming beauties, but they’ll need some help with plants, other natural methods, and some mechanical methods. With very specific care, some chemical-based options may be safe for fish but read product labels and reviews carefully before buying.

Some of the best species include:

  • Koi
  • Mosquito fish
  • Siamese Algae Eater
  • Chinese Algae Eater
  • Grass Carp
  • Mollies
  • Channel Catfish


There are a number of plants that can help reduce algae in ponds as well. These plants soak up a lot of the nutrients algae thrives on, meaning they deprive algae of these nutrients. Others provide shade and shelter, reducing the sunlight getting into the pond, which also helps prevent algae growth.

Some of the most effective plants for algae removal include:

  • Water hyacinth
  • Hornwort
  • Mosaic plant
  • Pickerel
  • Water lettuce

Barley Straw

One of the best organic ways to deal with algae is through the use of barley straw. This doesn’t kill existing algae, but it does help to prevent the growth of more. Put the straw into the pond as early in the season as you can though, as later in the season (read warm weather) it may cause a temporary algae bloom.  Avoid adding too much as well, as it may kill fish because of de-oxygenating the water. You should use about 2 pounds of barley straw per 1,000 gallons of water. In smaller ponds, use about 2 ounces per meter of water surface area.

    Summit Chemical Co Barley Straw Bales

2 packages of 2 barley straw bales in wrapper
    2 packs of 2 barley straw bales for pond


Algaecides are probably the most common approach to removing algae from a pond. These use chemicals – most of which are safe for plants and fish if used properly. They must only be used in stocked ponds that can be aerated however — algaecides will drastically reduce the oxygen in the water, which can kill fish.

Basic steps for using algaecides:

  1. Choose a good algaecide that comes highly recommended by fishpond owners.
  2. Follow the directions on the product you choose exactly as they are written out.
  3. Next, divide your pond into smaller quadrants for treatment, rather than all at once. This will help to reduce oxygen deprivation.
  4. Add an air pump for the duration of treatment to oxygenate the water.
  5. Clean your pond filter frequently throughout the whole treatment process.
  6. Remove the debris and sludge from the bottom of the pond before you start treatment, during the treatment, and after the treatment to ensure it’s most effectively working.
  7. Add activated carbon once the treatment is finished. This will help remove the algae residue.

    PondWorx Pond Bacteria for Large Ponds

bottle of PondWorx pond bacteria
    Algaecide for large ponds

    Sanco Industries Fountain Algaecide and Clarifier for Small Ponds and Fountains

Bottle of algaecide for small ponds and fountains
    Algaecide and clarifier for small ponds and fountains

A Gorgeous Pond is Just Around the Corner

water lilies floating in pond beside small fountain

With these tips, tricks, and new additions, you should have that pond cleared up and gorgeous in no time! Just have a little patience with things like plants and fish, and remember to make sure each choice works with the others to avoid potential issues like that catfish noshing on your algae eater.