How to Remove Algae From an Outdoor Pond

All ponds, man-made or natural, are subject to algae plumes.

Ridding a pond of algae makes it an enjoyable spot to watch fish and other water creatures. Algae blooms on small ponds are especially common in the spring. The winter debris of fallen leaves and yard waste provides a large array of nutrients on which the algae thrive. Clearing up the algae using some basic techniques will not only clean up the pond, but also help prevent the return of the undesirable pond scum. Homeowners usually encounter either string algae, which grows along the pond's sides and bottom, or plankton, which gives the pond the look of green soup.

Things You'll Need

• Kosher (or other non-iodized) salt
• Large tub for water draining
• Skimmer
• Bacteria
• Shade option
• Fishing net
• Water-dwelling plants

Instructions

String Algae

1. Remove the fish from the pond. The fish cannot be present in the water while it is being treated. Arrange for other accommodations during the cleaning process.

2. Drain the pond. Vacuum out the water into a large tub or container.

3. Add a large amount of Kosher or other non-iodized salt to the water. Depending on the size of the pond, you may need several boxes. Allow the salt to remain in the water for at least three days.

4. Wash down the bottom and edges of the pond with clean water. Remove any leaves or slime that may remain in the bottom.

5. Skim the treated water and filter out the salt before returning it to the pond and reintroducing the fish.

Plankton

1. Reduce the nutrients on which algae live. Skim the pond to remove all leaves or other yard debris. Clean the bottom of the pond to get rid any slime or other nutrient growths.

2. Shade the pond. Add aquatic plants, including lily pads, to the pond to assist in blocking out sunlight. Algae need sunlight to live. Planting shade trees or other types of shade is also helpful.

3. Add healthy bacteria. Garden stores carry healthy bacteria in various forms and brands. The addition of this substance assists in ridding the pond of algae by reducing the amount of food the algae have.

4. Install an aeration system. They add oxygen and prevent stagnant water. Aeration assists in ridding the pond of the bad bacteria often trapped at the bottom by stirring up the pond and providing oxygen to the deeper areas.

Tips & Warnings

• Seek assistance in identifying the type of algae growing on your pond if you are unsure of its origin. A professional gardener or landscaper should be aware of the two types.

• For ponds too large to drain, barley straw, added to the water, will reduce the presence of string algae.

• Avoid contact with any unidentified algae. Depending on the type of algae present, irritation of eyes and skin may occur. Wear gloves and goggles when cleaning the blooms.

References

• Pond Solutions: How Do I Get Rid of the Algae in My Pond?
• Lake Improvement: Algal Bloom Update
• Lenntech: Water Treatment Solutions
• ABC Ponds: Pond Algae Control

Resources

• Aquatic Community: What is Algae