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How to Use Lime to Remove Algae from Ponds

Nina Snow

A pond can add great value to your property or home. Along with the responsibility of landscaping around the pond comes the task of keeping the pond clean, fresh and clear. Algae blooms have a tendency to build up on the surface of ponds when excessive nutrients have been introduced to the pond water, usually through plant and animal decay and debris. Removing this algae for good requires safe use of hydrated lime (calcium hydroxide), a powerful corrosive that must be handled with care and kept out of the reach of children.

Rid your pond of unwanted algae.
  1. Calculate the volume of water inside the pond in gallons by measuring the length, width, depth and side slopes of the pond. An accurate measurement of pond volume can be difficult to asses. Various angles and slopes must be considered. Consult Table 1 of the "Lime Treatment" resource in the Resource section to attain the most accurate possible measurement.

  2. Determine the alkalinity of the pond water by using pH or total alkalinity test strips. Test several locations of the pond and then average the readings to determine the average alkalinity of the entire pond.

  3. Use the alkalinity level to determine how much hydrated lime is needed to treat the pond. Refer to Table 2 listed in the "Lime Treatment" resource found in the Resource section to determine how many 25-kg bags of lime must be used when treating the pond.

  4. Fill the custom applicator with a wet slurry of lime and water to apply the lime directly on the surface of the pond. Use all of the lime allocated by the measurement conducted in Step 3.

  5. Wait a minimum of three days before reintroducing fish or fauna into the pond.