Keeping Algae from Growing in a Pond


I have a pond that measures about 30' across and is about 5' deep in the very center, and I want to keep algae from forming without having to treat the water with chemicals, or clutter the pond with plants to block out the sunlight. I have seen ponds that are larger than mine and they have no plants and they are in direct sunlight and the water looks clean.


Will it help if I have certain types of stones like lime and sandstone in the pond? What would happen if I used salt water rather than regular city water to fill the pond? Please help!



Hi John,

First off, I applaud your intention to control algae without chemicals. It is not necessarily the easiest or most convenient fix, but most chemical solutions are only a temporary cure for the problem anyway.

There are several ways to keep algae under control in your pond without using chemicals. The key is finding which combinations of biological and physical components work best to keep your pond in balance. It may also take some time and patience to figure that out. It is not clear to me from your question whether your pond is stocked with fish, so disregard any of the following strategies that do not apply to your situation.

  1. Assist your plants in keeping your pond clean. Use a vacuum to siphon the bottom of the pond regularly. Remove dead leaves and fallen debris with a skimmer or rake as quickly as possible.

  2. Plant submergible aquatics. They take up nutrients in the water and release oxygen during the day to sustain fish and other aquatic life. They also remove excess nutrients from the water, which discourages algae growth. A rule of thumb is to plant one bunch of submerged plants per 1 square foot of surface area.

  3. Add a barley straw bundle (1 bundle per 1000 gallons of water). As it breaks down, barley releases an enzyme that acts like an organic algaecide. Bundles need sunlight to decompose, so if you try this strategy, don't let the bundles sink to the bottom of the pond. Attach a cork or a plastic soda bottle to the bundle to keep it afloat. After 2-3 weeks, the bale will decompose and provide effective algae for control for up to 3-4 months.

  4. Consider adding a biological filter and beneficial nitrifying bacteria (like Microbe-Lift or Bio-Pond) to your pond. These bacteria feed on the same nutrients as algae and will help keep algae bloom under control.

  5. Algae thrive in full sunlight. Adding enough floating plants (like water lilies, water lettuce and water hyacinth) to cover 1/3 of the surface of your pond will help provide shade.

  6. Use a pump to aerate water and keep it moving-especially near the side of the pond.

  7. Koi eat algae, but they also create waste. Limit fish to one inch of fish for every square foot of water surface in your pond.

Also, don't be afraid to approach and compliment the successful pond owners you see. They'll probably be more than happy to share their secrets with you.

Good luck!

About The Author: Ellen Brown is an environmental writer and photographer and the owner of Sustainable Media, an environmental media company that specializes in helping businesses and organizations promote eco-friendly products and services.

April 9, 20080 found this helpful

Barley straw in your pond will inhibit algae growth.

I have a small fountain with a prefilter; and the "spitter" part of the fountain--an ornamental frog--has a small UV light inside that the water passes by, and it kills any algae without chemicals.

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April 11, 20080 found this helpful

I had the same problem finally I had to get a filter, (a large 55 gallon drum with pvc pipes in it with holes. You can go on line and look up how to make one. It works good but you also have to provide shade for your pond. I just got rid of my pond because my back just couldn't take the cleaning anymore. At one time I had over 100 fish a mix of kaoi and gold fish. Also remember that gold fish give off ammonia and that is a toxin if it builds up. Good luck with your pond.

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May 10, 20080 found this helpful

Sterile Carp is the only way I have found to control the algae problem in my pond. They have to be special ordered. I have two in my pond. ~Janette~

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May 19, 20080 found this helpful

Plants, Floaters and Potted

Plants will soak up all those nutrients floating in the water that the algae also use to grow. The more plants you have the less nutrients in the water and no algae.

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July 7, 20080 found this helpful

I use an algae control product in my pond that is very natural and easy to apply. It is environmentally friendly, safe on fish, pets, humans and plants. You can even swim in the pond.

Have them give you a free quote. I'm sure it will not cost much considering it is a very small pond!

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May 24, 20160 found this helpful

Excellent post to peruse and helpful tips to used. koi fish is more fragile than other fish and delicate as well/For its survival, just Pondpro2000 is a liner which can be used safely.

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