How to Remove Algae From Your Pond Without Harming Fish

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How to Remove Algae From Your Pond Without Harming Fish

Maintaining a healthy pond is important for a number of reasons, including how it looks and also pond ecology and the health of your fish.  One of the most common questions we encounter about pond maintenance is “What to do with pond algae?” Algae in ponds is incredibly common and is not always bad, but the question of “How to remove algae from your pond without harming your fish”, is a very common concern.

What is algae? Is it always bad?

Algae is not one specific type of plant, but rather a broad  term that encompasses a large group of plants ranging from  small microalgae to large macroalgae (think seaweeds). When it comes to ponds, we are mostly discussing free-floating single celled algae (planktonic), colony mat algae (filamentous), or complex branched algae (Chara and Nitella).  In some circumstances blue-green algae (cyanobacteria) are the cause of concern.

It is important to note that most algae is not inherently bad. A pond without any algae at all is not ecologically balanced (fish cannot live in swimming pools). Algae is found all over the world in all kinds of ecosystems, actually forming the foundation for the aquatic food web. Our focus is on controlling excessive nuisance algae because getting rid of all algae is not a good idea if you want to maintain an ecologically balanced pond in which your fish will thrive.

Excessive nuisance algae (planktonic and filamentous) can be an unsightly problem and can lead to oxygen depletion problems that can kill fish. Additionally blue-green algae (cyanobacteria) can actually be toxic to animals, and even to people.  Heavy algae growth is generally considered undesirable no matter what type it is.  Generally speaking, the same conditions that lead to excessive growth of planktonic and filamentous algae are the same conditions that can encourage the growth of blue-green algae, specifically high nutrient levels (nitrogen and phosphorus), stagnant water, and lots of sunlight.  Therefore, the solutions are generally the same for all algae issues.


Pond Algae Solutions

Some healthy algae are good for all aquatic ecosystems, but how much algae and what kind of algae is enough depends on the type of pond you have. It is important to consider your personal uses and expectations for your pond. More algae growth may be acceptable in “fish ponds” or “nature ponds” than in “swimming ponds” or “decorative ponds”.

The best way to prevent algae problems is to stop them before they start. The best pond algae solutions are preventive. Eliminate the conditions that promote excessive pond algae growth to begin with.

Preventive Solutions

Most algae issues stem from an excess of nutrients in a body of water. Nutrients come from numerous sources such as lawn fertilizers, grass clippings, decaying leaves, goose droppings, leaking and failed septic systems, rain run-off from high nutrient areas, and others.  If you’re looking for a place to begin, controlling the sources of nutrients is a key starting point.

Other preventive measures include:

  • Not overfeeding fish.
  • Maintain a “filter strip” of native vegetation around the edge of the pond.
  • Avoid getting lawn clippings in the pond when mowing and trimming.
  • Avoid overuse of lawn fertilizers near the water and on areas that drain into the pond.
  • Controlling the number of waterfowl that utilize the pond (especially geese).
  • Aerate and circulate the pond with an aeration system.
  • Regularly apply beneficial bacteria to the pond to reduce available nutrients.
  • Using a water-dye to shade plant growth (including algae).


Algae Removal Solutions

Although taking preventive measures is the single most important step in a long-term algae control program, these measures take time to begin to be effective. Sometimes intervention beyond preventive measures is required due to the high nutrient condition of the pond to begin with or because of another factor like an unanticipated inflow of nutrients or other environmental factor beyond your control.  This leaves you with the question of “how to remove algae from your pond without harming your fish”.

Algae removal solutions include:

  • Mechanical removal of algae: if possible, gather it up and scoop it out. This may only be possible on small ponds.  This has the advantage of removing the nutrient value of the algae from the pond system.
  • Treat your pond with an approved algaecide that is appropriate for the fish in your pond. You must read and follow the label instructions to be sure that you don’t harm your fish.  Generally speaking, copper-based algaecides should NOT be used in ponds with Goldfish, Koi, or Trout.
  • Small ponds can experience some relief from algae by using Barley Straw based algae solutions, but these typically are not useful on large ponds.

Healthy Ecosystem, Happy Pond

Having a pond can be a delight if done the right way. Ponds provide entertainment for adults and children alike. When properly cared for, they can improve property value and create beautiful scenery. With a little extra care and investment in your pond you can make sure that it maintains a healthy balance.

We know that maintaining your pond can feel overwhelming, but the experts at Harrietta Hills can help you take care of your pond and keep it operating at its best, so that you can enjoy it for all it’s worth. Schedule a consultation with us so we can help you get the most from your pond.

Everything You Need For Your Pond And Lake!