Granular Bentonite Clay for Pond Sealing - 45 pounds

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  • Bentonite pond clay in 5 gallon pail
  • Granular Wyoming Bentonite Clay
  • Bentonite for ponds
  • Bentonite expands in contact with water and seals the pores in pond bottom soils


Granular Sodium Bentonite Clay for sealing pond soils. 45 lb pail.

One 45 pound pail = 0.63 cubic feet  Covers 9 square feet at 6 pounds per square foot.

Bentonite clay is a natural expanding clay sealant that when exposed to moisture can expand 15X or more creating a very effective pond sealant when applied correctly. 

Bentonite for Pond Sealing FAQ

Sodium Bentonite Source

Our bentonite clay is provided in granular form directly from the processing facility in Northeastern Wyoming. 

Bentonite Clay Application Rates for pond/lake bottoms

To properly apply bentonite to seal a pond, the pond must be drained and the bentonite clay then incorporated into the soil of the pond bottom and sides. The application rate for bentonite ranges from 2 pounds to more than 5 pounds per square foot depending on the soil characteristics. For clayey and silty soils, 2 pounds per square foot MAY be sufficient. For sandy soils 4 pounds MAY be sufficient and for soil containing gravel and rock, in excess of 5 pounds will be required to obtain a seal. Once the bentonite is applied, the soil should be disk harrowed to mix the soil and bentonite and then compacted.

Alternatively, a continuous blanket of bentonite can be applied to the soil and then carefully covered with clean soil or sand to prevent the clay from mobilizing into the water column. Placing the bentonite in a confined layer is far more effective as it forces the clay into adjacent soil pores creating a more effective seal.

Pond or Lake Dam Repair

For a leaking pond embankment, if the location of the leak has been identified, it may be possible to construct a core trench in the embankment to slow the leak. To install a core trench, excavate a minimum 12 inch wide trench to at least 3 feet below the pond bottom elevation. The trench should be located as far back from the pond edge as possible while still remaining on the flat top of the embankment.

The goal is to create an impervious core in the embankment which will not allow water to pass through. This impervious core can be created in a number of ways. Bentonite can be mixed with the excavated soil at a rate of 30% bentonite and 70% native soil. The material should be placed back in the trench and compacted with a trench roller, plate tamper, or excavator bucket in 6 inch lifts. 

Sealing around Leaking Outlet pipes

 Excavate at least 24" around the leaking outlet pipe.  Replace the excavated soil with 100% Wyoming Sodium Bentonite Clay.  Replace the native soil around the bentonite clay seal and compact in place with a trench roller or jumping jack compactor.

Ships via standard ground parcel service.   



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4 Reviews

  • 5
    Granular Bentonite Clay

    Posted by Rick on Jun 4th 2018

    Love this stuff!! Poured it into an area of a pond dam that has been giving me fits for years. Stopped the flow of water immediately!

  • 5
    Works like magic

    Posted by Matt on Oct 28th 2017

    We used the sodium bentonite to help with drainage issues around a 30" pipe that goes under our driveway. Water that flowed into the pipe was starting to erode the soil around the pipe near the bottom. We packed the bentonite in with the soil around the pipe and it really has steered the water away, back in to the pipe, as we intended..

  • 5
    Best stuff ever!

    Posted by Dr. Joe Niamtu, III Richmond, VIrginia. on Sep 3rd 2017

    I had a leak in the dam of a lake and ordered from this company and it arrived in 48 hours! All you do is to dump into the leak and it hardens like cement immediately, like magic. You can tamp it a bit but don't use your boots or it takes a long time to clean, it sticks to everything, that is why it works. Great company, great product. I keep some on hand for future leaks.

  • 5

    Posted by connecticut Mark on Jun 9th 2017

    easy to use. Produce expands as it sets. Great produce

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