How to Fix Cracks in Your Inground Pool—And Keep Them Gone

There are some really good things that happen to you when you own a pool, like backyard barbeques, low-impact exercise, and saving a ton of money with a variable speed pool pump. And make sure you don’t forget that side of pool ownership—because there will also be times when something goes wrong. There’s no way around it: cracks happen. And when they appear, they can bring a lot of stress along with them. It’s common for pool owners to assume the worst, such as underground leaking or a compromised foundation. Scary stuff, but trust me: cracks are common, and those nightmare scenarios are rare. Take a big breath.

Thankfully, as long as your pool doesn’t need a total makeover, fixing cracks in your inground pool is easy to do all on your own. And while they could potentially lead to bigger problems, they can usually get patched and stay patched—as long as you do it the right way, and soon. I’ll explain why your pool has cracks, why they should be repaired, how to choose the right plan of attack for you, and finally, how to fix the cracks in your pool—in three different ways. 

Why Did My Pool Crack in the First Place?

Don’t worry—you’re not alone. Just about any pool can crack, and some pools are more prone than others. Older pools that are made of concrete or gunite usually grow cracks, similar to how or skin changes as we age. These are usually pretty shallow and easy to patch up.

But if you have cracks that are consistently showing up, yikes. I hate to say this, but you might have a poor design and installation on your hands. And if your pool wasn’t designed or installed properly, your pool might be more susceptible to cracks that go right to the pool shell—layers below those harmless, superficial cracks. It’s these deep cracks that eventually cause bad leaks. If you’re getting cracks faster than you can plaster them, you might want to call in a professional to assess the way forward.

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how to fix cracks in your inground pool

Why Not Leave It As Is?

It’s tempting for anyone who owns a pool to wonder if they really do need to fix that crack, anyway. Let’s say they aren’t exactly worried about aesthetics, or are really into wabi-sabi (that’s the Japanese belief of embracing imperfection, and in some circles it’s all the rage). Basically, they’re the type of pool owners who don’t mind leaving pesky metal stains as they are. Aren’t cracks sort of the same deal?

If only we could be sure. The thing is, pool cracks range in severity. They typically aren’t serious, and only reach the surface layer of your pool. But sometimes they can reach deep enough to the shell of your pool, or indicate that your pool is leaking water. Not only could bad leaks get worse, but they’ll also cost you a lot of money in operational costs—when you have a leak, your equipment needs to work harder, which increases your energy bill. Cracks can also eventually affect your pool’s structure. I think we can agree we both wouldn’t want to deal with starting from the ground up on this one. 

First, Assess the Damage—And Know When to Drain 

Alright, so we know that not all cracks are equal. So how is yours looking? It might be a thin crack or a small spot that needs to be plastered. But your plaster might also be coming loose in chunks, is bubbling up, or is a long crack on the floor or down the side of your pool. If this sounds like your situation, you’re going to need to drain your pool. Be extra, extra careful—when you have cracking already occurring in your pool, you might be more at risk to experience the rare but dreaded pool pop up. Make sure you’re taking all precautions possible to prevent it from happening to you. 

If you have a thin, easy-to-tackle crack, you might not need to drain your pool at all. I’d recommend this for anyone who isn’t sure—it’s better to do all you can to avoid draining your pool when you have a crack or more already creeping along its surface. Plus, you’ll get to wear goggles and swim while you repair. That’s two birds, one cracked (for now) stone. 

With a Drained Pool: Plaster Repairs and Patching

Based on what you saw when you assessed your crack, you might need to repair your plaster or straight up patch it up. If you have a crack that is long or thick, you should get ready to repair your plaster. If you have bubbling, loose, or superficially crumbling plaster, you’ll need to patch it up. These two jobs are pretty different from one another, so you might need to give that crack another look to make sure we’re on the right track.

This next part I can’t stress enough: since you are draining your inground pool while there is at least one crack present, you’re going to need to take every precaution available to avoid the inground pool pop up. It’s a super rare occurrence, but there’s reason to believe that it’s more common when there are preexisting cracks involved. Don’t let this catastrophe happen to you and your pool—the last thing you want when repairing a crack is to experience your entire pool floor fissuring, as well as rising up out of the ground. It’s a worst case scenario.

Alright, no more horror stories. Listen, you’re doing your homework and you’ve already read up on how to prevent your inground pool from popping. You’re going to have a beautiful, smooth pool before you know it, so let’s get going.

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how to fix cracks in your inground pool

First, Get the Gear

If you’re simply repairing your plaster with a drained pool, you’re going to need a few essentials:

- Safety goggles

- Ear protection

- Heavy-duty work gloves

- Grinder or masonry saw

- A soft-tipped brush, like a painter’s brush

- Underwater sealer

- Pool plaster

- Grouting sponge

- Putty knife or trowel

If you need to patch your plaster with a drained pool, you’ll need the following tools: 

- Safety goggles

- Ear protection

- Hammer

- Masonry chisel

- Wooden pole

- Muriatic acid

- Soda ash

- Cement dye

- Pool plaster

- Pool trowel

- Grouting sponge 

How to Repair Plaster with a Drained Pool—In Six Steps 

1.     Safety first: put on your safety goggles, ear protection, and heavy duty work gloves. You’d better wear some closed-toe shoes, too—we’re used to wearing sandals around the pool, but this just isn’t the time.

2.     Using the blade of the grinder or masonry saw, cut the crack out about half an inch on either side, and half an inch deep. This cut should be diagonally toward the crack to create a dovetail. With the same blade, lengthen the crack by one inch on both ends. Remove the cut-out plaster.

3.     Rinse the crack and let it dry. Once it’s dry, brush it with the soft-tipped brush and apply a bead of underwater sealer along its edges. Leave about three-eighths of an inch of space for the plaster you’ll use to fill the crack.

4.     Mix the pool plaster according to the manufacturer’s instructions until it has the consistency of nut butter—thick enough to stay in place, but still easy to spread.

5.     Using a damp grouting sponge, lightly moisten the perimeter of the crack. Use the putty knife or trowel to apply to pool plaster and gently push it into the crack. Make sure it’s smooth and free from air bubbles. Then use the putty knife or trowel to scrape off excess plaster. Dab it with the grouting sponge to match the texture of the surrounding pool surface.

6.     Fill your pool back up as soon as possible. This is always my recommendation, but in this case the plaster will also cure better underwater. If you have more cracks to attend to, cover the patched spot with damp fabric—otherwise, it might dry too fast, shrink, and crack again. In either case, if your pool liner is left empty for too long, it can also get damaged. The sooner you fill up your pool, the better.

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how to fix cracks in your inground pool

How to Patch Plaster with a Drained Pool

 1.     Safety always comes first. Put on your safety goggles, ear protection, and heavy duty work gloves. It might feel wrong to wear work boots in your pool, but if there was ever a time, it’s now.

2.     Use the hammer and masonry chisel to remove loose plaster. Then, use the wooden pole to tap along the pool floor. If you hear a hollow sound, you might have found more loose plaster. Chisel them off as well, and clear away all the plaster you’ve removed.

3.     Next, use the chisel to create a few indents in the surface of the area you’re about to patch. The goal here is to make the surface a little rough, so that the new plaster adheres to it properly. Apply an acid wash to the surface by combining equal parts muriatic acid and water (seriously, be careful for this part). Then wash the surface off with soda ash to neutralize the area. If necessary, add cement dye to match your current plaster color.

4.     Mix the plaster according to the manufacturer’s instructions until it has the consistency of nut butter—thick enough to stay in place, but still easy to spread. To prepare your pool’s surface for the repair, dampen it with a wet grouting sponge using gentle dabs.

5.     Using the pool trowel, apply the plaster by pushing it into any corners, as well as the indents you made with the masonry chisel. Be sure to push out any air bubbles and smooth the surface as you go. Feather the edges of your new plaster into the surrounding pool surface, so that the area is even.

6.     Allow the plaster to set for fifteen minutes. Then, gently dampen the area and use the trowel to smooth the surface again. Cover the patch with wet fabric until you refill the pool, which should be as soon as possible. The plaster will cure best underwater, and if it gets too hot and dry can simply crack again. Once your pool is refilled, you’re done. 

I’d Rather Keep My Pool Full!

Hey, I don’t blame you! I’m all about saving time and money, and it’s no secret that draining your pool is incredibly costly and time-consuming. Not only do you have to do the actual draining, but you have to refill your pool with thousands of gallons of water, and balance your chemicals from scratch. Yeesh. If you think you can get around it, you might as well try.

Thankfully, there are putty and plaster mixes designed exactly for this purpose—they’re formulated to set underwater. Genius, right? You’d better get your goggles on for this one.

Get Your Gear

This is a job that doesn’t even feel like a job—especially if you were a whiz at combining newspaper, water, and flour for paper-mache in school. But regardless of your feelings about arts and crafts, you’re going to need a few supplies for this task. 

To repair plaster with a full pool, you’ll need:

- Swimming goggles (I wasn’t kidding!)

- Paint scraper or putty knife

- Wire brush

- Underwater pool plaster

How to Repair Plaster with a Full Pool—In Five Steps

With an underwater pool plaster mix in hand, you’re ready to go. Follow these instructions, and spoiler alert: you don’t have to get into the pool quite yet.

1.     First, mix the plaster according to the manufacturer’s instructions, and roll it into a ball.

2.     Put on your swimming goggles and hop on into the pool. (Might want to wear a swimsuit for this part, too!)

3.     Using the pointy end of your paint scraper or putty knife, rake along the crack to make sure it’s fully exposed. Brush the crack with the wire brush to remove algae, dirt, and debris.

4.     Push the underwater pool plaster ball into the crack with the paint scraper or putty knife.

5.     Using the paint scraper or putty knife, smooth the edges flat against the pool’s surface. Now it doesn’t get more straightforward than that. You’re done!

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how to fix cracks in your inground pool

I Knew We Could Patch Things Up!

That was kind of fun, don’t you think? Now that you’ve mastered filling one crack, you won’t have to feel any of that useless stress next time you see another appear—and hopefully, that’s a long time from now. And since you know you’re not running into any doomsday scenarios here, your next dive is going to be even more relaxed. You’ve put a lot of work into your pool, so now is the time to reap the rewards. Don’t forget sunscreen! And, enjoy.


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