What Kind of Lime Is Best for Ponds?

Whether you are planning to build a new pond, or need to treat an existing one, the type of lime you choose is critical. Lime is a chemical compound that can improve water quality and increase pond productivity. However, liming can also cause problems if used improperly. Fortunately, there are several different types of lime available, each with their own benefits and drawbacks. You should be able to determine what type of lime is best for your pond by considering the soil and water conditions in your area.

What Kind of Lime Is Best for Ponds Pros and Cons

Agricultural limestone is a popular choice for pond liming. These materials can be spread in the pond using a spreader or shovel. When spreading agricultural lime, you should apply about 500 to 1000 pounds per acre of surface area.

Agricultural lime can help control the pH of the pond, improving the health of the plants and reducing soluble phosphorus. This allows phytoplankton to grow more effectively. It is a good idea to test the pond’s pH before applying lime. A sample should be taken from the pond and analyzed at an accredited laboratory. If the pH is below 6.0, your pond will not be very productive. The best time to apply lime is during the fall or winter.

Depending on the water and soil conditions, the amount of lime you will need to apply will vary. Some types of lime may require more than a few applications over the years. If you have an overflowing pond, you may need to spread the lime more often. If you have a low-alkalinity pond, you can increase the hardness of the water by adding CaCO3 limestone. It can take up to four weeks for ag lime to begin working.

Dolomitic lime is another commonly used type of lime. This type is best suited for ponds, as it is a low-reactive form of calcium. It encourages the growth of beneficial microorganisms and can quickly increase water quality in stocked freshwater ponds. The downside to dolomitic lime is that it can cause fish kills if over-applied. You should always measure the magnesium levels in your soil before selecting a type of dolomitic lime.

The pH level of a pond can fluctuate widely, from 6 to 10 during the day. During the day, the pH is more alkaline than during the night. In order to maintain a stable pH, you should have a total alkalinity of 20 parts per million or higher. Adding limestone or dolomitic lime will raise the alkalinity of the pond. You should not add limestone if the pond has an acidic pH. You should also avoid using agricultural limestone if the pH of the pond is above 8.3. Crushed agricultural limestone can be very expensive, and is very difficult to dissolve in high-alkalinity water.

Liquid lime can be a convenient alternative for frequent liming applications. This type of product has higher neutralizing power than traditional dry lime. It is easier to distribute, and can be used in small ponds. However, you should consider the cost per unit weight, and the total neutralizing power of the product.