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Fiberglass vs. Concrete Pools: The Complete Comparison

Concrete and fiberglass are two of the most common liners for in-ground pools. They require vastly different maintenance schedules, and their costs vary dramatically. Your pool’s liner determines which chemicals you can use, how long it’ll last, and more.

When it comes to fiberglass vs. concrete pools, concrete pools last longer, whereas fiberglass pools are much more affordable. Fiberglass pools can’t fit a freeform layout, though. On the other hand, concrete pools are a bit more abrasive and cost more to maintain. Both options are excellent liners.

Throughout this article, I’ll show you the differences between fiberglass liners and concrete pools. I’ll also break down the pros and cons of each to help you determine which liner you want for your swimming pool.

Which Is Better: Fiberglass or Concrete Pools?

It’s hard to choose between fiberglass and concrete because they both offer plenty of benefits. Concrete pools (which are technically made of plaster) are the most common option between the two. While vinyl pools are the most popular choice for above-ground pools, plaster pools are the top choice for in-ground pools.

A fiberglass pool might be better for someone on a budget or which specific pool equipment. However, concrete pools are the most familiar option for many pool owners. Without further ado, let’s dive into the pros and cons of both pool liners to help you decide which one you want in your swimming pool.

Pros of Fiberglass Pools

  • Fiberglass pools are one of the most budget-friendly options on the market. You can get a fiberglass pool for a fraction of the price of a concrete pool. The maintenance costs are also cheaper since you have to use fewer chemicals and you don’t have to brush the liner as often.
  • Most fiberglass pools are ideal for salt systems. Fiberglass naturally lowers the pool’s pH. Since salt systems increase the pH, it’s a perfect combination. You can skip the weekly dry acid or soda ash treatments for monthly routines. Furthermore, you won’t have to worry about the salt building up on the side of the liner.
  • You don’t have to worry about calcium buildup or high-pH issues most of the time. Plaster pools leach calcium into the water, but fiberglass pools don’t leach anything into the pool. The naturally low pH can be balanced with the previously mentioned salt systems or soda ash, but there’s no need for calcium removers.
  • Fiberglass is much more flexible than concrete, which means minor earthquakes and settling won’t affect it. There won’t be any cracks or warped concrete in a fiberglass pool. The material’s flexibility gives you more bang for your buck, letting you focus on maintenance instead of repairs.
  • Fiberglass liners feel much softer than most pool liners. Everyone I know who’s switched to a fiberglass liner has instantly noticed a difference. It’s not abrasive and hard, nor is it squishy and fragile. Fiberglass has the best feeling of any pool liner on the market, especially if you brush it weekly.

Cons of Fiberglass Pools

  • These pools aren’t as durable as concrete and pebble pools. Fiberglass is flexible, but it’s not too resilient against blunt force trauma. It’ll tear or break if someone drops something heavy on the bottom of the pool, especially if there’s no water to slow the fall.
  • The fiberglass is prone to dropping the pH, so you’ll need to add soda ash regularly. Pool Mate’s pH Increaser comes in a 10-pound bag, making it ideal for fiberglass pool owners. One scoop per treatment is often enough to prevent acidity and low-alkaline swimming pools.
  • You can’t make any shape you want with a fiberglass pool. Fiberglass is limited to a handful of shapes. You won’t be able to design lavish shapes and sizes. Many pool builders limit fiberglass pool depth because they don’t want to come back for warranty work if the liner tears from the water’s weight.
  • An ill-maintained fiberglass liner will lead to itchiness and eye irritation. Fiberglass is quite uncomfortable to the skin. However, fiberglass pool liners come with a soft gel coat that prevents the fiberglass from getting into the water. Algae and extreme acidity can destroy the liner, sending the fiberglass into the pool.
  • Fiberglass doesn’t last as long as concrete pool liners. You’ll get a couple of decades out of a fiberglass liner, but it’s about half as long as concrete pools. This may or may not be an issue, depending on how long you intend to keep the house and swimming pool.

Now let’s get into the pros and cons of concrete pools.

Pros of Concrete Pools

  • Concrete pools can be made in any shape and size. You can design the most elaborate concrete pool at any depth and free form customization. Those with grottos and built-in water features should opt for the creativity of a concrete pool. You can also add a spa to the combo.
  • You can get up to five decades out of a concrete swimming pool. Anyone who wants to live in the same location for life should choose a concrete pool. They offer an excellent resale value, and you’ll rarely have to worry about replacing rebar or gunite.
  • These pools can be acid washed to remove the top layer and reveal a brand-new layer of plaster. You can use muriatic acid, which is the same liquid used to lower the pool’s pH. Scrub the concrete with a stiff wire brush and liquid acid to refinish the surface and bring back the new appearance.
  • You can add stones or pebbles into the concrete’s design. Pebble tech is one of the most visually appealing swimming pool designed. The pebbles line the bottom and sides of the pool, making it look much more natural. You can create a concrete pool that looks like a river or lake without leaving your backyard.
  • Concrete pools can be emptied and refilled without caving in, unlike fiberglass pools. However, it’s best not to leave the concrete pool dry for too long, or it’ll develop cracks. Fiberglass pools cave inward and break apart if they’re empty for too many days without being at least ⅓ full.

Cons of Concrete Pools

  • Concrete pools are significantly more expensive than fiberglass pools. You can spend more than twice as much on a plaster pool, and that doesn’t include the potential water features. Additional spas, concrete slides, and other features can double the cost of a basic concrete swimming pool.
  • Plaster pools take much longer to install compared to fiberglass or vinyl. Most concrete pools take a few months to complete. In contrast, most companies can install a fiberglass pool in a few weeks. The shape, size, and local demand will determine how long your pool takes to install, though.
  • The plaster in a concrete pool can be rough and abrasive. It’s a porous material that feels like a mix of concrete and sandpaper. While it’s not uncomfortable to walk around, the plaster liner is quite rough for diving and sliding. Regular brushing will prevent the liner from getting too abrasive.
  • Concrete pools leach calcium into the water, which increases the calcium hardness and causes stains. The only way to get rid of calcium is to partially drain and refill the pool. Always test the calcium levels before adding salt or calcium and before filling the pool after an acid wash.
  • You’ll have to add pH reducers to combat the ever-rising pH and alkalinity in a concrete pool. The plaster slowly increases the pH and alkalinity. Add muriatic acid to the pool to maintain the chemistry. Test the water and keep the pH between 7.2 to 7.8 and the alkalinity between 80 to 120.

While they have many differences, there are a handful of similarities between fiberglass and concrete pools. I’ll cover everything you should know in detail below.

How Are Fiberglass and Concrete Pools Similar?

Fiberglass and concrete pools are similar because they’re both durable, easy to maintain, and require pH adjustments. They also need algaecides, chlorine treatments, and regular brushing. You can use the same pumps, filters, salt systems, and heaters for fiberglass and concrete pools.

Here’s a quick list of similarities you should know about:

  • Both pool liners need to be treated for algae. Removing dead algae will prevent cloudiness and stop new algae blooms from growing. Furthermore, it’ll stop health hazards in their tracks. You can use a copper-based algaecide to keep your vinyl, fiberglass, or concrete liner algae-free.
  • Fiberglass and concrete pools should always be put in the ground. Vinyl is the only material you should consider for an above-ground pool. The flexible fiberglass and heavyweight concrete can corrode, crack, and fall apart if the pool isn’t sunk into the ground. You’ll need PVC plumbing (copper is outdated and thin plastic isn’t enough).
  • You can use rebar to support concrete and fiberglass pools. Your pool will sink into the soil and fall apart if there’s nothing to support it. Furthermore, the rebar prevents the pool from warping and tearing the liner. Acidity and poor maintenance can reveal the rebar through the bottom of the swimming pool.
  • Brushing is an essential part of owning any pool liner. The LALAPOOL Swimming Pool Brush is an 18-inch stiff brush that removes algae, stains, and other debris from your fiberglass or concrete pool. It attaches to any universal pole and includes snapping clips to prevent it from falling off.
  • Any pool vacuum works in concrete and fiberglass swimming pools. Vacuuming the pool prevents leaves, twigs, and other natural debris from causing algae blooms. You can choose a robotic, manual, suction-side, or pressure-side pool cleaner. Make sure you remove and empty the vacuum regularly.

Don’t let the similarities convince you that these liners are the same; They’re far from it. They require similar maintenance, but the overlap isn’t enough to justify one over the other.

Who Shouldn’t Get a Fiberglass Pool?

People who want a custom pool shouldn’t get a fiberglass pool. They don’t have as many shapes and sizes as concrete pools, not to mention the lack of potential additions. These pools are quite cookie-cutter, which means you won’t have a unique pool style.

You might also want to avoid fiberglass pools for these reasons:

  • Extreme temperatures can damage the liner, so it’s best to avoid them if you live in a very hot or icy cold place. You can use pool heaters and solar covers to prevent these temperatures from becoming problematic, though.
  • If you don’t want a pre-cut swimming pool, steer clear of fiberglass liners. They can’t be built in your yard, which means you have to choose whatever is readily available.
  • The soil under a fiberglass pool can warp the liner and change its shape. It’s important to have sturdy soil, compacted sand, or rebar under the pool.
  • Excessive amounts of direct sunlight can ruin the topcoat, so those without solar covers should avoid fiberglass liners. The sunlight can cause spider cracks that send small tears in every direction.
  • Since fiberglass pools are pre-cut, you’ll need a massive opening on your side yard to let the pool builders come into the backyard. It needs to be wide enough to fit the narrowest part of the pool, which is often between seven to ten feet.

Who Shouldn’t Get a Concrete Pool?

Anyone who doesn’t have at least $25,000 in their budget shouldn’t choose a concrete pool. They have expensive installation and material costs, not to mention the long-term maintenance. You’ll have to brush the concrete regularly, so it’s best to expect to replace the brush each season.

Concrete pools might also be a bad idea for these reasons:

  • If you have a lot of natural debris around the pool, you might want to avoid plaster liners. Leaves, grass, dirt, and other debris can stain the plaster and cause deterioration.
  • You shouldn’t get a plaster pool if you don’t get the highest quality available. Countless pool companies offer cheap plaster pools that break apart, so it’s important to get the best plaster or none at all.
  • Those without access to calcium hardness for swimming pools shouldn’t get a concrete pool. Plaster liners need an adequate amount of calcium that slowly depletes via evaporation and refilling the water.
  • If you prefer a colored pool liner, opt for vinyl or fiberglass. While companies can dye the plaster, it’s difficult to achieve a thorough coloring (the dye also fades over time).
  • Plaster is a bad idea without access to muriatic acid. Liquid acid is banned in some places and limited in others, so it’s important to know when and where you can get it beforehand.

Now that you know everything about concrete pools and fiberglass pools, it’s time to find out which one is best for your backyard.

Which Pool Liner Is Best for You?

It’s hard to know which liner is best for you. Consider the price, maintenance, longevity, feeling, and appearance to make your final decision. These five factors make a world of difference. Concrete pools offer a familiarity that you won’t find in fiberglass pools, but they can be heavy on the wallet.

Here’s a breakdown of each of these five factors:

  1. What’s your price range? Fiberglass pools are much cheaper to own and maintain than concrete pools. If you get a salt system, they’ll cost even less since you won’t have to deal with pH adjustments too often. However, you can easily spend more on a fiberglass pool if you get a massive layout.
  2. Do you have enough time to maintain the liner? Fiberglass pools need to be brushed every so often, not to mention the vacuuming. However, concrete pools need to be brushed on a weekly schedule. They can get porous and invite black algae, which is extremely difficult to remove.
  3. How many years do you want to use the swimming pool? You’ll get about 25 years out of a fiberglass pool and 50 years out of a concrete pool. That being said, you can resurface the pool to reset the clock. Structural supports last indefinitely (or until they’re removed or damaged by earthquakes).
  4. Does the softness of the liner matter to you? Fiberglass liners are much softer than any other liner. Concrete liners are a bit rough, though they don’t seem to bother most people. Vinyl liners are soft, but they don’t have the gel texture of fiberglass liners. Furthermore, they don’t have durability and longevity.
  5. Do you care about customized sizes and shapes? You can customize a concrete pool however you want, but fiberglass pools are limited to premade shapes and sizes. I recommend making a diagram of your backyard to know what kind of pool you should get. Remember to consider the options of local companies.

Answering these questions should point you in the right direction. Your swimming pool’s liner is one of the most important decisions when it comes to owning a pool. However, every liner material needs good equipment, reliable plumbing, and a sanitizer to stay in good condition.

Author

  • Jonah Ryan

    Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he's not writing for Temperature Master, he's usually writing for his own websites, LawnCareLessons.com and DIYByHand.com.