Keeping Algae from Growing in a Pond

By Ellen Brown

Question:

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!

John

Answer:

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.

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

Answers: Keeping Algae from Growing in a Pond

Read answers for this question below.

By 07/07/2008

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.

http://www.adbio.com/site_maps/algae.htm

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

By (Guest Post) 05/19/2008

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.

By 05/10/2008

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~

By Madeline (Guest Post) 04/11/2008

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.

By 04/09/2008

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.

Keeping Algae from Growing in a Pond

Q: I am desperately looking for a way to stop algae from growing in my small pond with goldfish in it. It is a container pond and I have tried everything. Does anyone have any home remedies?

Thanks in advance,
Michelle

A: Michelle,

Algae multiply rapidly under the right environmental conditions-especially in water containing excess nutrients (phosphate and nitrate) while having access to a lot of sunlight promoting photosynthesis. Effective control requires depriving algae of food and/or light.

Here are a few natural ways to control algae:

Don't overstock your pond with fish. Decomposing organic waste from fish provides a continuous supply of nutrients for algae bloom and string algae. Keep your pond clean by regularly vacuuming the bottom to prevent build up of these nutrients along with frequent partial water changes.

Shade can be supplied with plants such as water lilies and water hyacinth. However, because the pond's primary source of oxygen is at the water's surface, too many surface covering plants can result in low oxygen levels (signaled by gasping fish). You'll need to provide additional aeration and/or reduce the number of fish in your pond if you want to maintain extensive surface-covering plants.

Consider shading the pond's surface with a type of canopy made from shade cloth or lattice. Many aquatic gardeners find this inhibits growth of algae while protecting flowering aquatic plants from excessive sunlight and heat. This method will also protect your koi's colors and protect them from overhead predators.

If all fails, there are a number of algae controlling additives available that are safe for fish and aquatic plants.

RE: Keeping Algae from Growing in a Pond

pine straw (07/17/2005)

By ken.

RE: Keeping Algae from Growing in a Pond

Cover at least 60% of the top of your pond with water plants, they will starve out the algae. Also keep pond shaded as sunlight promotes algae growth. (07/18/2005)

By Anonymous

RE: Keeping Algae from Growing in a Pond

Try throwing a handful of new copper pennies in. The copper sulfate discourages algae growth in water. I use them in my aquariums. This is not an "instant" fix, takes a little time for copper to leach out of pennies, but it does work! Happy gardening. Joyce (07/18/2005)

By Joyce

RE: Keeping Algae from Growing in a Pond

I have been having the same problem with my small pond (100 gallon). I resorted to taking the pond out and pressure washing it, then when I put it back in and refilled it i started treating it with "ALGAE DESTORYER ADVANCED". A big bottle of it at Walmart sells for $8.93 and it only takes 2 teaspoons every 3 or 4 days to treat a pond the size of mine. So far the water is staying nice and clear and the fish seem healthy (its safe for fish and plants). (07/20/2005)

By mamaboo

RE: Keeping Algae from Growing in a Pond

Find some small pelleted food for your fish. Only give them enough food that they can eat in 5 minutes. I have a small pond and I don't feed the fish every day. I was told that if you have some floating pond plants in your pond the fish will find enough food to live on for several days. Also you might try to find some "water shade" tablets. They turn the water a beautiful shade of dark blue and that helps keep the sunlight out so the algae won't grow so much. I found some water shade at Home Depot in the pond department. Remember some algae growth on the sides of your pond is normal and healthy so don't try to eradicate all of it. Hope this helps. (07/30/2005)

By Jeri