Limestone Uses in Ponds

Increase Nutrients

• The quality of the pond water directly reflects the quality of the soil, and if the proper nutrients are not present, all life in and around the pond will suffer. Limestone, either calcite or dolomite, is added in fish ponds with acidic soil or low alkaline levels. This boosts the availability of phosphorous, calcium, carbon and magnesium to fish and aquatic plants. The enhanced nutrient cycling will help dissolve organic matter that has collected in the water.
  
  

Increase and Buffer pH

• Carbon dioxide is produced by the respiration of plants and animals, and in water it has a pH reducing effect, especially at night. Plants, such as algae, photosynthesize in the sun and consume carbon dioxide, which causes the pH of the water to increase. The liming of a pond increases the carbonate concentration, or alkalinity, which breaks down the free carbon dioxide and creates a buffer that maintains the pH level between 7 and 8.5.
  
  

Sterilize

• Slabs and boulders of limestone will wear down over time.Jupiterimages/Photos.com/Getty Images
  
  Hydrated lime (slaked or builders lime), may be suggested when there is concern of disease, pests or toxic levels of copper sulfate in a pond. This will increase the pH quickly and dramatically, often to 12 or higher, and kill everything in the water. Fish, and anything else that you want to live, must not be in the water during the use of this treatment. Rearing ponds often use this treatment prior to filling a new pond, or one that is being treated for infection.
  
  

Application

• Applying lime in fall or winter permits enough time for it to dissolve and support maximum production the next growing season. While ponds with fresh water flowing through continuously normally need to be limed annually, those with little or no outflow typically benefit from sufficient liming for several years after application. Monitoring the pH and alkalinity levels establishes the necessary liming frequency.