Noxious plants in ponds include blanket weed, duckweed and the water fern. The plants often grow in ponds that have too many nutrients, such as phosphate and nitrate. The extra nutrients come from runoffs of fertilizer, animal waste or sewage. If you don't control these plants during early stages of growth, they can take over the whole pond surface. Ridding your pond of these noxious plants can be difficult unless the underlying cause is discovered and also can be hard work depending on the size of your pond.
Drain the pond using a large bucket or water pump, depending on the size of your pond. You'll want to dispose of the old water so you can add new water that has the right amount of nutrients for your pond.
Remove the noxious plants from the bottom of your pond using a net with a handle. Make sure that you wear rubber gloves when removing the plants.
Spray a pond-cleaning disinfectant all around the bottom and sides of your pond. Scrub the areas using a brush and make sure any algae or waste is removed. Spray off the areas with a hose before refilling your pond.
Refill your pond with water that has a balanced pH that is appropriate for your pond. It's also best to have a clean filter that is properly running to remove any algae from your pond.
Maintain your pond and remove any sediment from the bottom of the pond at least two to three times a week. Add barley straw to your pond to help get rid of excess algae.