Pond Academy

Pond Sealer: How to Seal a Pond Naturally (Best Products & Methods)

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If you’ve confirmed your pond has a leak due to a hole or crack in the liner or foundation…

It’s time to seal that baby!

But, what kind of pond sealer should you use for best results?

Let’s look at the best pond sealer products on the market today and help you find the right choice for your unique pond.

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What Is Pond Sealer

Pond sealer is a product used to fix small holes and cracks in the foundation of your pond.

did you know Important

It’s good practice to seal any holes or cracks in your pond as quickly as possible. Besides the obvious issues with water loss and fish health, cracks in your foundation will only worsen if you don’t repair them in a timely manner.

The type of pond sealer you’ll use depends on a few factors:

  • The type of foundation your pond has, whether it be a pond liner, concrete foundation or natural soil/clay foundation.
  • The size of the hole or crack
  • Whether you can/want to drain your pond to repair the hole

did you know Important

Is your pond really leaking? Ponds naturally lose water due to evaporation. Especially in warmer climates. To find out if you have a leak and exactly where that leak is, check out our guide on How To Find A Leak In A Pond In 2 Simple Steps.

Once you’ve identified where the leak is in your pond it’s time to get to sealing.

But first, here is a quick comparison of the top pond leak sealers we’ll be covering below, and the type of pond they are used for.

Best Pond Sealant Comparison Chart

Description Type Price
Gold Label Underwater Sealant Gold Label Underwater Sealant Pond liner sealant SEE PRICE »
Cofair Tite Seal Pond Liner Repair Kit Cofair Tite Seal Pond Liner Repair Kit Pond liner sealant SEE PRICE »
Pond Armor Non-Toxic Pond Shield Epoxy Paint Pond Armor Non-Toxic Pond Shield Epoxy Paint Concrete pond sealer SEE PRICE »
DamIt - Rapid Leak Sealer DamIt - Rapid Leak Sealer Soil/clay sealer SEE PRICE »
Natural Waterscapes Granular Sodium Bentonite Clay Natural Waterscapes Granular Sodium Bentonite Clay Soil/clay sealer SEE PRICE »
TotalPond Waterfall Foam Sealant TotalPond Waterfall Foam Sealant Waterfall sealer SEE PRICE »

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How To Stop A Pond From Leaking

The sealant you’ll need to stop your pond from leaking depends on the type of pond foundation you have. We have them broken out by pond liner (a liner sheet usually made of rubber or PVC), concrete foundation or a natural soil/clay foundation. Skip to the section that best describes your pond for specific instructions on how to stop your pond leak using the recommended product.

Pond Liner Sealant

If you have a hole or tear in your pond’s liner, then you have a few options to repair it. One involves draining your pond and one doesn’t.

did you know Important

If the tear is longer than 5” we recommend replacing the liner completely. Check out our Pond Liner guide to find the best liner for your pond or water garden.

Underwater Pond Liner Sealant

Gold Label Underwater Sealant is an effective way to seal tears in your pond liner without having to drain your pond's water.

This product uses moisture as a curing agent making it ideal for underwater sealing. And it’s safe for fish ponds, as well.

This pond liner sealant works on all types of liners including rubber, PVC, EPDM, plastic, and more.

Application
  • Step 1: Clean the surface of the pond liner around the tear.
  • Step 2: Apply the underwater sealant directly to the tear.
  • Step 3: Allow the sealant to cure for at least 24 hours

Gold Label Underwater Sealant

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Gold Label Underwater Sealant

Pond Liner Patch Kit

Pond liner patch kits are an effective way to repair tears and holes in all different types of liners including EPDM, PVC, polyethylene and polypropylene liners.

Keep in mind, that you will need to drain your pond water to at least a few inches below the tear in order to install the patch. If that’s not an issue, I would recommend using the patch kit over the underwater sealant as it tends to work better in our experience.

Application
  • Step 1: Drain your pond. You don’t have to completely drain the entire pond. Just be sure to drain it so the surface of your pond's water is at least a few inches below the tear. This will allow you enough room to apply the patch. Be sure to follow our guide on how to drain a pond quickly and easily.
  • Step 2: Clean the surrounding area of the tear with the included solvent wipes
  • Step 3: Using the dry scrub sponge, scrub and dry the damaged area.
  • Step 4: Remove the backing paper from the patch and apply over the tear.
  • Step 5: Use the seam roller to apply pressure to the patch and ensure a tight bond.

Cofair Tite Seal Pond Liner Repair Kit

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Cofair Tite Seal Kit

Concrete Pond Sealer

Concrete ponds, while very durable, will start to form cracks over time. This is especially true if you live in an area that has extreme temperatures.

Sealing a concrete or cement pond is a different process than sealing a pond liner. So, how do you seal a concrete pond that leaks?

One common and super effective way is with an epoxy pond sealant paint like Pond Armor!

Pond Armor Pond Sealant

Pond Armor is a non-toxic epoxy designed to prevent cracks and holes from forming in concrete, cement, wood, brick, and many other types of ponds. And it can be used to repair small cracks by essentially gluing the cracked foundation back together.

This liquid pond sealer is designed for underwater use and is a plant and fish safe pond sealant.

And it’s available in many different colors including clear, black, competition blue, gray, green, tan, white and sky blue.

Application
  • Step 1: Prepare the surface according to the manufacturer’s directions.
  • Step 2: Mix the sealer with the hardener. Only mix enough that you can use within 30 minutes.
  • Step 3: Apply the sealer to the damaged area.
  • Step 4: Let dry. Typically takes around 24 hours to fully cure.
  • Step 5: Inspect the area and touch-up as needed.

Check out Pond Shields tutorial on concrete crack repair for ponds.

Pond Armor Non-Toxic Pond Shield Epoxy Paint

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Pond Armor Non-Toxic Epoxy Paint

Soil & Clay Pond Sealer

If you have a natural soil or clay pond foundation, common with a lot of farm ponds, then the two most popular options are polymer pond sealers and bentonite sealers.

Polymer Pond Sealer

Soilfloc Pond Sealant and Damit Pond Sealer are two of the most popular polymer-based pond sealers on the market today.

Basically, a polymer sealer is just a powder that you sprinkle onto the surface of your pond. The powder has a positive charge that draws it to the bottom of your pond and eventually is drawn into the cracks in your ponds foundation. Once in the cracks, the powder will expand and plug the crack, effectively stopping the leak.

Both Soilfloc and Damit are non-toxic and safe for humans, fish, and other aquatic life.

Application
  • Step 1: Broadcast the powder evenly over the surface of your pond. You can do this from a boat (in larger lakes or ponds) or in shallower ponds you can walk very slowly through the water. If using Soilfloc, you’ll have two powders to evenly spread across your pond (Damit is just one powder). Be sure to use the recommended amount of powder as described on the product package.

And that’s it! For best results:

  • Don’t apply powder on windy days. You want the water to be as calm as possible.
  • Use a fertilizer spreader or hand scoop to more evenly spread out the powder during the application process.
  • Be sure to remove any heavy vegetation prior to application so they don’t impede the ability for the polymers to enter the cracks.
  • If you are applying the powder while walking through your pond, be sure to broadcast it out behind you (not in front of you).

DamIt - Rapid Leak Sealer

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DamIt Pond Sealer Product

Bentonite Pond Sealer

If you’re looking for how to seal a pond naturally, then look no further!

Bentonite clay pond sealer is essentially a natural clay that expands up to 15 times when exposed to water to create an effective seal in the cracks of your pond or lake.

While you can sprinkle bentonite clay over the surface of the water, it’s most effective when your pond is drained, and it’s applied directly to the foundation.

Application

There are a few different application techniques for pond sealing with bentonite clay, with the most popular being the blanket method:

  • Step 1: Drain your pond and clear the foundation of any vegetation and debris.
  • Step 2: Remove the top 5 inches of soil from your water bed and set to the side.
  • Step 3: Fill in any holes, cracks or gaps with a mixture of bentonite and soil (1 part bentonite and 5 parts soil).
  • Step 4: After all holes are covered, a layer of bentonite clay should be applied evenly over the entire foundation.
  • Step 5: Replace the 5 inches of soil we removed in step 2.
  • Step 6: Refill the pond with water.

So, how much bentonite does it take to seal a pond? The answer depends on the type of soil(s) your ponds foundation is made up of.

Type of Soil Sealant Amount
Clay 1 - 1.5 lbs. per sq. ft
Sandy/Clay Mix 2 - 2.5 lbs. per sq. ft
Sand 3 - 4 lbs. per sq. ft
Rock or Gravel 5 - 6 lbs. per sq. ft

Always refer to the manufacturers recommended amounts when applying bentonite clay.

Natural Waterscapes Granular Sodium Bentonite Clay for Pond Sealing

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Natural Waterscapes Granular Sodium Bentonite Clay for Pond Sealing Product

Pond Waterfall Sealer

A common, but often overlooked source for pond leaks is in and around the waterfall.

TotalPond Waterfall Pond Foam Sealant

TotalPond Waterfall Foam sealant is simply a polyurethane foam that is used to fill, seal, and bond rocks that are used for waterfalls.

This moisture-cured sealant expands 2 to 3 times to effectively fill any gaps or cracks to prevent leakage.

It’s also safe for fish and aquatic plants.

Application
  • Step 1: Shake the foam sealant can well and screw on the nozzle adapter.
  • Step 2: Test on an experimental surface to make sure foam sticks.
  • Step 3: Fill in any gaps, cracks, or crevices about 1/3 of the way to allow for expansion.
  • Step 4: Allow 12 to 24 hours to fully cure.

TotalPond Waterfall Pond Foam Sealant

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TotalPond Waterfall Pond Foam Sealant Product

*Important: Follow the manufacturer’s directions on the packaging for the most up-to-date information when using any pond sealant product.