You can seal a leaky pond that already contains water by using bentonite clay, either as a slurry or in granular form.
Sealing a Pond with Bentonite Clay
Bentonite clay is an absorbent aluminum phyllosilicate clay consisting mostly of montmorillonite. It swells significantly when wet, making it an effective sealant. Here's how to use it:
1. Bentonite Slurry Method
- Preparation: Mix bentonite powder with water to create a thick, creamy slurry. The consistency should be similar to paint.
- Application: Pour the slurry directly onto the surface of the pond water. The slurry will sink to the bottom and begin to seal the leaks. For larger ponds, it's best to apply the slurry in sections, working your way around the perimeter.
- Dosage: The amount of bentonite needed depends on the size and severity of the leak. A general guideline is to use approximately 1-2 pounds of bentonite per square foot of pond surface area for minor leaks. For more severe leaks, increase the application rate.
2. Granular Bentonite Method
- Preparation: Purchase granular bentonite. This form is easier to spread evenly.
- Application: Evenly spread the granular bentonite over the surface of the pond. As the granules sink and become saturated, they will expand and create a seal.
- Dosage: Similar to the slurry method, use approximately 1-2 pounds of granular bentonite per square foot of pond surface area for minor leaks. Adjust as needed based on leak severity.
Important Considerations:
- Water Chemistry: The effectiveness of bentonite can be affected by water chemistry, particularly high salt content. Test your pond water before application to ensure bentonite will properly swell and seal.
- Even Distribution: Even distribution of the bentonite is crucial for effective sealing.
- Monitoring: After applying bentonite, monitor the pond's water level to assess the effectiveness of the seal. You may need to reapply bentonite in areas where leaks persist.
- Pond Size: For very large ponds, sealing with bentonite while full can be challenging and expensive. Draining and applying bentonite to the empty pond bed may be a more efficient option.
