Only the most hardcore pond owners go for a concrete pond. However, it comes with its own set of advantages and issues. Concrete is porous and invites in lime and other chemicals that can harm your precious fish. To avoid that, you need a solution- waterproofing.

A popular way to waterproof a concrete pond is to use a G4 concrete sealer. It will go on to seal the concrete and form a resin-ish coating that will block the pores so that lime or any other chemicals can’t leach into the pond.

Let me guess, you are curious! I knew it, so I prepared a treat for you in advance. I’ll show you how to make a concrete pond waterproof easily; all you need to do is scroll below…

Making a waterproof concrete pond: 2 Quick Solutions

How To Make A Concrete Pond Waterproof

There are quite a few ways to reach that end; I’ll discuss them elaborately.

Method 01: Using a Pond Liner

The easy and affordable way to waterproof a concrete pond is to simply use a thick liner. You’d have to install the liner the same way you’d do for a sunken pond liner.

But there is a bit of a problem with that. In case there are kinds of stuff like bottom drains or return hoses built inside the pond, you’d have to cut the pond liner and place them securely around these and any other fixtures. This could create an opening.

Another problem is as most concrete ponds are kind of a squared shape, the liner might have to be pleated, and you may end with an uneven liner, which creates folds that are not easy to clean and makes way for a debris buildup.

If the liner isn’t smooth, you are going to need an underlay that’ll have to do more heavy-duty work to protect the wall. Another option is to have an entire heavy-duty liner itself.

Another method you can adopt is to apply fiberglass into the interior of the pond. Fiberglass is extremely durable support for a pond. However, it is a bit expensive, and this kind of application isn’t perfect without a professional’s help.

Usually, people who use fiberglass in the interior contact a company because they use various resins and it is likely to have toxins. They have professionals to ensure the safety. I shouldn’t have to tell you what a dent that it makes to the wallet, do I?


So naturally, I don’t suggest depending on pond liners to make it waterproof ultimately; while it does protect your pond, I’m not sure it’d be smart to trust it to do something which isn’t it’s function.

Don’t worry; I have another route.

Method 2: Coating with a pond sealer

G4 Pond Paint and Sealer

There is another method that people love for waterproofing a pond, that is using a pond sealer. Painting the render’s final layer with a G4 sealant is a widely used tactic to combat a concrete pond’s problems.

After applying the G4 sealant, first, you have to let it dry. When it’s dried off, it’ll create a resin-like coating that prevents any lime from infiltrating the pond’s interior, thus waterproofing it.

That is the general philosophy of this operation. You can also use this coating on various other structures like walls, fountains, or statues, even flagstones.

So, out of the two common ways of waterproofing a concrete pond, this is the better one. Now, let’s head on to the steps of using a G4 sealant.

How to use G4 concrete pond sealer to waterproof a pond?

It is not a really hard job to do; you just have to be methodological in your approach. If you’ve come this far and made a concrete pond, in comparison to that, this is as easy as having bread and jam. Please follow the instructions carefully:

Let the concrete be hardened for four weeks for curing. Afterwards, take a normal paintbrush and gently coat the concrete using the G4 sealer. There is no need to apply a primer.

While you can let the concrete be weather damp, still the ideal situation would be to let it dry.

The tricky part about this method is that you have to paint everything in a day because you will have to apply the coating multiple times.

So, I just suggest that you set a date that has a good forecast, then assemble everything you need at least one day before the big day. Wake up early that day, and get to work. Ask a friend to help out if you feel like it’s too much for you alone.

Now here’s the main course of action, apply the first coating by using a paintbrush. When you’re done, it’ll feel a bit tacky, but don’t worry, it is bound to be like that, and it won’t be present on the finished product.

After 1 or 1.5 hours, apply the second coating. You have to repeat the process for a third and fourth coating. Be vigilant, and don’t let the time difference of applying two layers be more than 4 hours.

You noticed I’m hard stuck on the repeated coatings, right? That is because if the G4 dries separately in different layers, then it’ll be less durable. It won’t be your most ideal result now, would it?

After you’re done with applying the final coating, let it rest for three days to cure.

You can finish the G4 in 2 ways- black or clear. There are some differences between the two. I’ll go by them down below:

  • The clear finish needs three coatings of clear G4 that needs 550g coating per square meter.
  • On the other hand, a Black finish needs 2 coatings of clear G4 with an additional two layers of black G4. You’ll need a total of 410g clear and 400g black G4 per square meter for this finish.

Importance of waterproofing a concrete pond

While a concrete pond is long-lasting and those who can bear its expenses get a good benefit out of it, the problems concrete brings due to its porous nature hits a sore spot.

It absorbs water and is seeped away from the pond, simultaneously bringing in lime that affects the pH of the pond adversely. There is a likelihood that other chemicals might also be able to infiltrate the pond; if any of that is toxic for your fish, then you’re heading for a sad ending.

So, you need to waterproof your concrete pond in case you don’t want your pond to end up like that.

No more leaky ponds

Imagine having put so much effort into building a concrete pond, then you see it leak in lime and other chemicals, I don’t know about you, but it’d break my heart.

Fortunately, my guide on how to make a concrete pond waterproof will never let you feel that sadness. Just remember to coat it the way I described.

Your pond is most likely to last for decades, so please treat it nicely.

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