What is LSI?

Posted on April 9, 2024October 9, 2025 by kristin

LSI and Fiberglass Pool Chemistry

The Langelier Saturation Index (LSI) is a formula that the gunite pool industry adopted to determine water balance and predict whether water will form calcium scale or dissolve it. Some pool industry professionals insist you should focus strictly on LSI balance, but for fiberglass, that advice can damage your pool. However, an LSI calculator can be helpful for fiberglass pool owners as a secondary tool in keeping critical factors of water chemistry within fiberglass-safe target ranges.

What Are Fiberglass-Safe Water Chemistry Target Ranges?

pH: 7.2 to 7.4
Total Alkalinity (TA): 80 to 120 ppm
Free Chlorine (FC): 1 to 3 ppm
Cyanuric Acid (CYA): 30 to 50 ppm
Calcium Hardness (CH): Less than 120 ppm (NEVERt add calcium)
Total Dissolved Solids (TDS): Less than 1,500 ppm (or up to 1,000 ppm above your salt level)

Always use a stain and scale control or chelating and sequestering agent as part of routine care and for winterization. Never use calcium hypochlorite or any calcium-adding products in fiberglass pools. When pH, calcium, and chlorine are all elevated at the same time, the risk of damage to the fiberglass pool gelcoat increases significantly. If only one or two are high, the risk of damage is lower but still present.

What is LSI?

The Langelier Saturation Index was developed in the 1930s by Dr. Wilfred Langelier to help cities predict whether water would deposit calcium carbonate scale inside pipes or dissolve it. The concept later made its way into the pool industry because it’s an easy way to check water chemistry with respect to calcium carbonate.

Simply put, LSI looks at pH, alkalinity, temperature, and calcium levels together and estimates whether water is likely to scale (represented with a positive-number LSI) or dissolve calcium (negative LSI).

Why is LSI Secondary for Fiberglass Pools?

Concrete and plaster pools contain calcium in their walls. If the water is too “hungry” (what pool pros call “aggressive water”), it pulls calcium out of those surfaces, causing rough spots or etching.

Fiberglass pools are different. The shell doesn’t contain calcium, so aggressive water won’t leach anything from it. Instead, the bigger risk is the opposite: too much calcium in the water. When high calcium combines with high pH or high chlorine, it can cause discoloration on the gelcoat. That’s why adding calcium to “fix” LSI—something that works for concrete—can actually damage fiberglass.

How Do I Use LSI in a Fiberglass-Safe Way? Practical Steps to Take

Think of LSI as a final check after you’ve set your fiberglass targets.

Dial in the targets first: pH between 7.2 and 7.4, TA between 80 and 120 ppm, FC at 1 to 3 ppm, CYA at 30 to 50 ppm, and CH less than 120 ppm.
Check LSI last: Aim for roughly -0.30 to +0.30.

- In cold water, from late fall through winter, a slightly negative LSI is acceptable.
- Do not push water chemistry factors outside of fiberglass-safe ranges in order to hit perfectly balanced 0.0.

If LSI is too positive and water is scale-prone:

- Bring pH toward 7.2 to 7.4 without overshooting high.
- Confirm TA is within 80 to 120 ppm.
- Do not add calcium. Keep using your stain and scale control.

If LSI is too negative and water is aggressive:

- Make sure pH is not below 7.2 and adjust gently.
- Bring TA within 80 to 120 ppm.
- A cold-weather LSI total slightly below -0.30 can be acceptable for fiberglass.

Looking for more information on water chemistry and fiberglass pool maintenance? Explore Thursday Pools’ Ultimate Fiberglass Pool Maintenance Guide.

And if you’re ready for personalized advice or want to talk about water chemistry ranges with a local pool pro, connect with an independent Thursday Pools dealer near you.

Frequently Asked Questions About LSI

My LSI is +0.5 but my pH is 7.6. Should I add calcium to bring it down?

No. For fiberglass, keep calcium hardness levels less than 120 ppm. Lower pH toward 7.2 to 7.4 and verify total alkalinity between 80 and 120. Keep using a stain and scale control product. Calcium may fix LSI for concrete pools, but it causes more harm than good in fiberglass.

What if my fill water is hard?

Use a stain and scale control product and manage pH and total alkalinity. The goal is to prevent calcium fallout onto the gelcoat, not raise calcium.

Can I “balance for LSI” during winter?

You can allow a slightly negative LSI in cold water, but always stay within fiberglass-safe pH and total alkalinity ranges, keep calcium hardness less than 120 ppm, and use additional stain and scale control at pool closing.

Do I need to calculate LSI every time I test my pool water?

No. Focus first on fiberglass-safe water chemistry ranges for pH, alkalinity, chlorine, and calcium.

Why is calcium hardness so important for fiberglass pools?

Fiberglass shells don’t need calcium for structural protection, unlike concrete pools. Too much calcium in fiberglass pools leads to scale, discoloration, and rough surfaces, so always keep levels less than 120 ppm. If you have hard source water and your calcium is high, be sure to use a stain and scale control product.

How Much is the Smallest Fiberglass Pool?

Posted on October 14, 2022August 26, 2025 by kristin

We can’t read minds, but chances are that if you landed here by searching “How much is the smallest fiberglass pool?”, you are interested in both a small fiberglass pool and are concerned with costs. In this post, we’ll define small fiberglass pools and address some cost-related questions.

About Small Fiberglass Pools

Many fiberglass pools are over 600 square feet (e.g., more than 37.5 feet long by 16 feet wide). Comparatively speaking, a small fiberglass pool may be under 400 square feet. This size will fit into many smaller yards, take up less space, and is still fun and functional. To give you an idea of what that looks like, here are some Thursday Pools small fiberglass pool designs and their dimensions:

Small Fiberglass Pool Prices

Our general suggestion for getting a rough ballpark estimate for our fiberglass pools is to multiply your linear square feet by $1500. Of course, it’s more complicated than that, and you would need to get an estimate from a pool dealer near you to get firm numbers. Every case is different, and fiberglass pool prices vary according to a number of factors, including:

Installation Factors Affecting Pool Prices

Ease or difficulty of accessing your backyard
Excavation complications (e.g., rocky or sandy soil)
Permits and variances
Barrier requirements (e.g., fencing or safety pool cover)
Electrical work
Plumbing (especially rerouting septic fingers)
Dirt hauling
Standard pool equipment (filtration system, skimmer and jets, a vacuum head and pole, vacuum hose, skim net, wall brush, thermometer, and chemical test strips)
Additional pool equipment (e.g., pool heater, automatic vacuum system, salt generator)
Backfill
Restoration

Optional Factors Affecting Pool Prices

Landscaping and hardscaping costs
Patio furniture
Ladder
Slides
Mosaic tile
Specialty lighting (such as LED lights)
Water features such as deck jets, bubblers, and waterfalls
Swim jet system or spa features

Are Small Pools Cheaper?

Yes. Generally speaking, small pools are less costly than larger pools. Not only do they save space in your backyard, but they also cost less to build initially due to fewer building materials being used and easier installation. Additionally, they cost less to maintain. A smaller pool requires less water and fewer chemicals and is generally easier to maintain than a larger pool.

Are Fiberglass Pools More Expensive?

Fiberglass pools are inground pools that are more expensive than above-ground pools. They are typically more expensive than a vinyl liner pool, but according to Home Guide, a fiberglass pool is generally 10 to 20 percent cheaper than a gunite pool. Additionally, fiberglass pools cost less to maintain than traditional pools. Over the course of 10 years, a fiberglass pool will save you 75 percent on maintenance costs as opposed to a concrete pool.

How Much Does a Fiberglass Pool Cost?

Fiberglass pools range from $45,000 to $85,000 on average, but smaller pools may run less. Use the Thursday Pools Pool Cost Calculator to get an estimate for your pool project based on size and desired options. This tool can help you better understand the cost breakdown behind your pool.

Whether you are looking for a small fiberglass pool because you have a small backyard or you are trying to save money, our best advice is to let us get you in touch with an independent pool dealer in your area. A pool dealer can give you the best estimate based on all the factors that affect pool pricing and can answer your project-specific questions.

Wanting a Pool in Your Small Yard?

Posted on April 26, 2022August 26, 2025 by krista

No matter the size of your yard, creating a staycation-worthy backyard is within reach. Small fiberglass pools fit compact spaces without sacrificing style, comfort, or function. They offer a low-maintenance, budget-friendly solution with options like plunge pools and other ultra-compact designs, making it easier than ever to add a beautiful, refreshing pool to even the smallest backyard.

Is a Small Pool Worth It?

Absolutely! Small pools offer a smart, stylish solution for homeowners who want all the benefits of a pool without overwhelming their outdoor space.

With a compact design, you’ll have more room for other backyard features—like a lounge area, firepit, or outdoor kitchen—so you can truly enjoy a well-rounded outdoor living space. Smaller pools also mean easier upkeep, lower chemical use, and reduced energy costs, making maintenance a breeze.

And when it comes to your budget, going smaller can free up funds for extras like built-in seating, a tanning ledge, or an automatic pool cover. Best of all, small fiberglass pools come in a variety of layouts to suit how you plan to use your space—whether that’s relaxing, exercising, or entertaining a few close friends.

What Are Some Small Pool Options?

Before exploring specific designs, it’s important to understand the three main types of inground pools. Each offers unique benefits, and the best choice depends on your space, budget, timeline, and how involved you want to be with long-term upkeep.

Concrete (Gunite) Pools

Install Time: Approximately 3 to 6 months
Maintenance: Around 4 to 5 hours per week
Cost: $50,000 to $120,000+
Customization: Fully customizable in shape, size, and features

Concrete pools are known for their design flexibility and durability. If you have a very specific vision for your pool’s shape or want to maximize every inch of your yard, concrete offers the freedom to create a one-of-a-kind layout. Keep in mind, though, they take the longest to install and tend to require more hands-on maintenance and chemical use over time.

Vinyl Liner Pools

Install Time: Approximately 4 to 8 weeks
Maintenance: About 2 to 3 hours per week
Cost: $25,000 to $65,000
Customization: Custom sizes and shapes available

Vinyl liner pools are more affordable upfront, and builders can tailor them to fit many different backyard configurations. They’re a practical option if you want some customization without the higher price tag of concrete. However, the vinyl liner will eventually need replacement, which adds to long-term upkeep and costs.

Fiberglass Pools

Install Time: About 3 weeks
Maintenance: Around 1 hour per week—or less
Cost: $30,000 to $85,000
Customization: Limited to pre-designed shapes and sizes

Fiberglass pools come pre-formed from factory molds, which speeds up installation and simplifies maintenance. While you won’t have as much design flexibility, many models are available in compact sizes with built-in seating, tanning ledges, and other features that make the most of smaller spaces. The smooth, non-porous surface also resists algae growth, meaning fewer chemicals and less time cleaning.

Each pool type brings something different to the table—whether it’s complete customization, affordability, or ease of care. If you’re working with a smaller yard, all three can be viable options depending on your goals and preferences. Talking with a pool professional can help you weigh the trade-offs and find the best fit for your backyard.

Small Backyard Pool Ideas

Whether you’re looking for a true plunge pool or just a space-saving pool design, there are plenty of options for full-size enjoyment in smaller spaces. Below are some of Thursday Pools’ most popular compact models, each offering unique features to fit your lifestyle and yard size.

Plunge Pool Options

These pools are deeper than they are expansive, perfect for cooling off, standing, soaking, or even light exercise. A plunge pool is ideal for homeowners who want the experience of a luxurious inground pool without the footprint of a full-size one.

Sea Turtle

Size: 9.5′ x 19.5′ | Depth: 4′6″

The Sea Turtle is a true plunge-style pool with a flat bottom and generous bench seating on both sides. It’s perfect for standing, stretching, or simply soaking on hot days—all while fitting comfortably into a smaller yard.

The Nook

Size: 8′4″ x 16′ | Depth: 4′8″

The Nook offers a balanced blend of comfort and practicality. With a built-in bench and consistent standing depth throughout, it’s ideal for water aerobics, casual conversation, or simply unwinding. Built-in entry steps and a non-skid surface make it a safe and easy-to-maintain plunge pool.

The Nest

Size: 8′4″ x 16′ | Depth: 4′8″

Petite and purposeful, The Nest is a compact plunge pool for relaxing, cooling off, and casual soaking. It features a flat bottom, wide entry steps, and is auto-cover ready—making it a stylish solution for tight spaces.

Other Compact Pool Options

These pools aren’t plunge-style, but still work well in smaller yards. They offer more swimming space and family-friendly layouts, often with added seating or space for games.

Lil Bob

Size: 13.5′ x 27.5′ | Depth: 4′6″

Lil Bob is all about flexibility. With wrap-around bench seating and a flat, even depth, it’s great for light swimming, games like water volleyball, or simply lounging with friends. It’s a compact design with room to move.

Titus

Sizes:

12′ x 26′ | Depth: 5′5″
14′ x 33′ | Depth: 5′10″

Titus offers a larger swim area while still fitting in smaller backyards. Its rounded shape and built-in seating create a comfortable space for both activity and rest. It’s a good choice if you want a pool that supports swimming as well as relaxation.

Wading Pool

Sizes:

9′ x 9′ | Depth: 1′6″
11′9″ x 13′9″ | Depth: 1′6″

Great as a stand-alone feature or a pool add-on, the Wading Pool is ideal for small children, a quick dip, or cooling off without getting fully in. It offers shallow, safe fun in a small footprint.

Wet Deck

Size: 8’1” x 14′ | Depth: 1′

The Wet Deck is a shallow splash zone perfect for sunbathing or letting young children play. Use it alongside another pool or on its own as a refreshing, low-maintenance backyard water feature.

Ready to Make a Small-Pool Splash?

Small yard? No problem—smart design and the right pool can help you make a big splash anywhere. Whether you prefer a traditional fiberglass pool, a plunge pool, or a more compact design, there’s a perfect option to fit your space, style, and budget. Connect with a Thursday Pools dealer to explore what’s possible, check out the Pool Cost Calculator for a quick estimate, and browse our Idea Book for extra inspiration.

What are My Rectangle Fiberglass Pool Shell Options?

Posted on April 18, 2022June 16, 2025 by krista

Commonly, pool buyers ask, “what shapes do fiberglass pools come in?” While the simple answer is that fiberglass pool designs are primarily either rectangular or freeform, you may be surprised by the remarkable variability of fiberglass pool shell options. The sizes, varying depths, and vast assortment of features available in fiberglass pools allow you to tailor your choice depending on your yard size, style, and the activities you want to enjoy in and around your backyard pool. Rectangular-shaped pools have clean, sharp lines and lend to a traditional elegant or modern setting. They maximize the swimming area and perimeter yard space. In this post, we’ll describe our rectangle pool shell options.

Goliath

The Goliath is big on style and functionality. Offering the best of both worlds, Goliath provides plenty of room for entertaining and swimming.

A wide-open swim lane down the pool’s center is conducive to lap swimming or floating with friends.
Bench seating flanks the steps for ample room to relax and socialize.
Two sets of curved entry steps in the shallow end and swim-out ledges in the deep end provide easy entry and exit areas or another option for sitting.

Monolith

Monolith is the only Type One diving pool design in Thursday Pools’ collection and is suited for pool owners looking to take a plunge, float and relax.

The 40’-long pool has an 8′ 6″ deep end and a large, flat-bottomed shallow end perfect for playing pool games.
The angled steps make it easy and safe to enter and exit the pool.
The shallow-end bench makes an excellent spot for relaxing and socializing.
The dual deep-end benches make it a little easier for those deep-end lovers to enter and exit the pool or sit and rest.

(Note: *Thursday Pools strongly recommends that diving boards and slides not be installed or used with its pools, given the inherent dangers associated with diving boards and slides in residential pools. These dangers include brain, spinal cord and other severe permanent injuries, and death. For that reason, Thursday Pools does not manufacture or sell diving boards or slides. If, despite this warning and recommendation, the owner decides to install or use a diving board or slide, the owner assumes all risks inherent with a diving board or slide, and Thursday Pools further warns that diving boards and slides require minimum depths and distances and must be installed and used in strict compliance with the equipment manufacturer‘s specifications and ANSI/NSPI, ANSI/APSP, and ANSI/APSP/ICC standards, as well as in compliance with all applicable laws, rules and regulations. The owner is responsible for making sure the pool is appropriate for diving boards and slides and otherwise meets all standards and laws for diving pools, and the owner must consult the diving board or slide manufacturer and/or installer as to the appropriateness of the pool for the diving board or slide and that its installation, location and use meet all standards and laws for diving and slide pools.)

Aspen

The Aspen is a best-seller with five different available sizes to fit almost any yard. Sunbathers and swimmers alike rate this pool a favorite.

A large, luxurious 12-inch deep tanning ledge can comfortably accommodate two lounger chairs while leaving plenty of room to enter and exit the pool.
A wide-open swim space is ideal for swimming laps.
Curved steps stretch across the width of the pool and offer easy entry and exit.
An extended bench makes for a nice spot to enjoy a beverage or engage in great conversation.
Deep-end swim-outs are perfect for relaxing in the sun or watching other swimmers do their thing.

Grace Beach Entry

Thursday Pools’ beach entries (Patent US 10,472,839) are zero-entry fiberglass pools with a gently sloping entry into the water. Grace creates a resort feeling and is a stunning social centerpiece for entertaining.

A gently sloping beach entry makes it easier for people of all ages and their pets to enter and exit the pool. The area also makes a great spot for sunbathing and can accommodate two lounger chairs.
A wading area is perfect for cooling off shallow waters and can double as a play area for small children.
The extended bench provides a place to relax and enjoy a conversation.
Dual deep-end swim-outs can be used for exiting the pool or just chilling out.
Even with all the places to relax and socialize, Grace still has a wide-open swim area for those wanting to exercise.

Lil Bob

Lil Bob is perfect for games and the swimmers who are content to watch the action from the wet sideline. A standing depth, flat bottom design with two 12-foot-long benches helps Lil Bob keep things sporty and social.

Full-width ergonomic steps make it easier for everyone to enter and exit the pool.
A standing-depth, flat bottom design makes Lil Bob the ideal pool for water games and activities. It’s regulation size for water volleyball.
Each of the 12 foot long and 18 inches deep, two facing benches make excellent court-side seats and a conversation area.
Lil Bob includes an open swim area thanks to strategically placed benches and steps.

Lil Bob LX

Lil Bob LX is an extended version of Lil Bob, designed to include a tanning ledge and wading area with integrated bench seating. Everyone can find a favorite spot in Lil Bob LX.

A large tanning ledge easily accommodates two lounger chairs while leaving room for entry and exit.
Just past the tanning ledge, a wading area provides ample space to entertain your littlest ones while the big kids get a workout in the game-ready, open swim area.
Generous wraparound benches allow family and friends to enjoy hours of relaxed conversation.

Spirit

Spirit appeals to social butterflies, swimmers of all ages, and water activity lovers.

With its court-sized flat-bottom design, Spirit allows pool-goers to get their game on.
Extended bench seating and full-length steps at both ends of Spirit invite swimmers to rest and socialize.
At 4’6″ deep, swimming is comfortable for a variety of ages.

Sea Turtle

While it is a smaller pool, Sea Turtle is still big fun. Perfect for smaller yards, Sea Turtle gives you swim and play space and can accommodate therapy jets.

It is medium depth throughout for standing and chatting or even a little game.
Wraparound benches flank the entry steps, creating an intimate conversation area where your group can relax the day away.

While each of the rectangle fiberglass pool shell options have different features, all pools by Thursday Pools are:

Quicker to Install: Fiberglass pools are manufactured in a controlled environment and then shipped to the site for installation, taking just a few weeks on average during typical pool installation seasons.
Aesthetically Pleasing: The durable gelcoat finish of a Thursday Pool retains its beautiful appearance.
Non-skid: Take a glance at a Thursday Pools fiberglass pool, and you might think it’s slippery. Don’t let the shiny appearance fool you. The surface is non-skid and non-snag – perfect for kids and pets! (Of course, always be careful when entering and exiting any swimming pool.)
Durable: We build fiberglass pools from Thursday Pools to last. The multi-layer composite fiberglass construction and innovative design features make fiberglass very robust.
Feature-laden: The designers at Thursday Pools pay attention! They understand what people want and deliver pool designs that allow homeowners to get peak enjoyment out of their pool.
Lower maintenance: Thursday Pools are resistant to algae and mineral deposits and do not have seams or the porosity of other pool types. That saves you hours of work and many dollars every year. With proper water chemistry, they can last with minimal maintenance or need for acid washing, resurfacing, or re-lining.

Do you think a rectangle fiberglass pool design is right for you but are still unsure of the size and features you want? Our Pool Selector Tool can help you narrow down your choice.

What’s the Cheapest Inground Pool Cost?

Posted on March 21, 2022June 16, 2025 by kristin

If spending more time with loved ones (or by yourself) outdoors is climbing on your “should-have” list, and you have the space for an inground pool, you may have started an online search. Being a conscientious consumer, you could have landed here searching for the cheapest inground pool or even the “cheapest inground pool near me.” While no inground pool is “cheap,” this post gives an honest comparison of costs for vinyl liner, gunite, and fiberglass pools. We know an inground pool is a significant investment, so we hope this post will help you make an informed decision about inground pool costs.

Vinyl Liner Inground Pool Costs

Vinyl liner pools are generally the cheapest inground pool type with regard to upfront costs; however, their costs can increase significantly based on several factors. A ballpark figure on the average price of an inground vinyl liner pool is around $25,000 to $65000. Some constraints with vinyl you’ll want to be aware of:

Unique freeform shapes can add to your upfront price, as well as vinyl replacement costs, as manufacturing a custom liner adds time and materials.
High-end features such as bench seating or wraparound steps can add to your cost and may lead to further maintenance needs due to vinyl’s tendency to attract algae and become slippery.
The lifetime ownership, including the annual maintenance cost will offset some initial cost savings.
As previously mentioned, vinyl liner pools can attract algae, so you must clean them more often to keep them at bay. Expect to spend (or pay someone to spend) around four to eight hours per week on vinyl liner pool maintenance.
You could estimate maintenance expenses around $11,000 to $17,000 over ten years, excluding liner replacement costs.
Vinyl liners usually need to be replaced about every seven years (or fewer if the pool hasn’t been properly maintained), costing about $3,000- $7,500 on average.

Gunite Inground Pool Costs

Gunite pools typically cost the most to install, and their prices are the most varied across the country, depending on your location. In some regions, they are the high-volume choice of installers, and installation costs can be competitive. You tend to see more gunite installations in sunbelt states that are not subject to the freeze/thaw cycle. The national average price of a gunite pool is between $50,000 and $120,000. Here are some of the cost factors for gunite:

Freeforms generally cost more than basic shapes, and depending on how complicated the design is, the complexity may add more cost to the bottom line.
Each build is custom. Gunite costs more as you add features and options.
The porosity of gunite attracts algae and mineral deposits. It requires significant time and money to keep it clean. Expect to spend (or pay someone to spend) around four to eight hours per week on gunite pool maintenance.
Gunite pools usually require an acid wash to remove algae and mold every three to five years, and due to multiple acid washes, they often require replastering about every ten years.
Based on the average costs of regular pool maintenance tasks and requirements (such as acid washing, general cleaning, replastering, electrical/chemical usage, etc.), concrete pool owners can expect to pay $27,000 to $40,000 over 10 years for maintenance.

Fiberglass Inground Pool Costs

Fiberglass pools will usually fall in the middle between vinyl and gunite on the initial installation cost. However, lifetime ownership and annual maintenance costs tend to be lower than vinyl and gunite. HomeGuide’s 2024 inground pool cost guide reports that the average fiberglass pool price is between $30,000 and $85,000. However, many pool builders in our network report that their customers choose packages closer to $70,000 and $135,000. Some considerations of fiberglass pools relative to cost include:

Regardless of shape, the pricing is relatively consistent at around $1,800 per linear foot, except for beach entry fiberglass pool designs which tend to cost about 15 percent more.
Built-in features such as wraparound steps and benches, tanning ledges, and swim-outs do not cost extra, but they must already be part of the design, as fiberglass pools are built from pre-existing molds.
Easy access is essential to keeping costs down because they are delivered in one piece and not built on-site.
They are resistant to algae and require the lowest maintenance compared to the other inground pool types, needing only about an hour or two per week, and their ten-year cost for maintenance is around $5,000-$15,000.

Factors Affecting Any Inground Pool Cost

Some factors drive up costs, no matter what pool type you choose.

What’s the cheapest inground pool shape? Pool size affects the price of fiberglass pools rather than shape. However, for gunite and vinyl liner pools, the more complex the shape, the higher the cost.
What’s the cheapest pool size? Generally speaking, small inground pool costs tend to be less than larger ones for installation and maintenance.
Site conditions factor into pricing. Clay, sand, rock, and groundwater can all pose problems when installing any pool. Average excavation costs range from $2.50 to $15.00 per cubic yard for easier soil conditions, but more challenging conditions can cost $50 to over $200 per cubic yard.
Insurance companies and states or local agencies may require pool fencing. Fencing costs average around $15 to $25 per linear foot.
Pool cover prices vary. An automatic pool cover costs $8,000 to $20,000 installed and $1,000 to $3,600 for a manual cover.
Extra features add to the price. Additional features such as heaters, bubblers, deck jets, cascades, LED lighting, slides, and diving boards will also add to the cost.

Cheapest Fiberglass Pool Designs

At the end of the day, we are a fiberglass inground pool manufacturer and that is what we know best. So if you decide to look at lifetime costs, want to stay on the cheaper side, and want to check out some less expensive small fiberglass pool designs, one of the following may be the pool for your lifestyle:

Aspen. The smallest available size is 12’ x 25’ with a depth of 5’1”. The Aspen features a wide tanning ledge, full-length steps, and an extended bench. And it has a wide-open swim area and courtesy ledge throughout the deep end.

Goliath. Like Aspen, this pool comes in multiple sizes, the smallest being 12’ x 25’ with a depth of 5’4”. The Goliath offers a surplus of swim space, along with dual-corner entry steps, and shallow and deep end benches.

Sea Turtle. This pool comes in one size: 9.5’ x 19.5’. Sea Turtle is a flat-bottom pool with a depth of 4’6”, which is ideal for socializing and water activities. Walk-in steps and long benches make it family and pet-friendly, and it’s perfect for entertaining guests.

Pearl. Measuring 15’ x 25’ with a 3’9” depth, the Pearl is a shell-shaped pool that is unique. It’s great for socializing and sunning, with room for two ledge loungers and wrap-around benches.

More Tools for Inground Pool Estimating

If you’re looking for ways to get ballpark prices for pool installation, there are inground pool cost estimator tools out there. Get an estimate on your dream fiberglass pool project with our Pool Cost Calculator. If you are not sure which design is right for you, try our Pool Selector Tool to help you narrow it down. Finally, your best tool for the most accurate estimate and advice is a pool builder. Get connected to a pool builder near you and become one step closer to some of the best memories of your life.

Everything You Need to Know About Inground Pools: Comparing Fiberglass, Vinyl, and Gunite Options

Whether you’re making a mad dash to the end or first dipping your toe into the wading-area waters of inground pool ownership, this guide includes everything you need to know to compare the three inground pool types. From installation processes and long-term maintenance needs to overall costs and exciting design possibilities, you’re in the right place to begin your inground pool conversation and compare fiberglass, vinyl liner, and gunite (concrete) pools.

How Much Does a Small Inground Pool Cost?

Posted on December 15, 2021August 26, 2025 by krista

Understanding how much a small inground pool costs is an important first step when planning for a pool in a compact backyard. Smaller pools offer a practical solution for limited spaces, delivering style, function, and enjoyment without the size or expense of a full-size pool. With the right approach, they can enhance your outdoor space while fitting your budget. Whether you’re dreaming of a quiet retreat or a stylish entertaining spot, a small inground pool can transform even the smallest or simplest backyard into something extraordinary.

Why Choose a Small Inground Pool?

Small inground pools offer numerous benefits for homeowners with smaller yards, families, or those seeking an efficient and stylish pool solution. Thoughtful and creative designs enable these pools to maximize limited outdoor spaces while maintaining sophistication and practicality. Their streamlined size contributes to easier maintenance, reduced water and chemical use, and lower long-term ownership costs. Despite their compact dimensions, these pools do not compromise on features or visual appeal. With careful planning, a small inground pool can become a striking focal point of your backyard, providing a perfect balance of relaxation, recreation, and fitness opportunities. For example, flat-bottom models are particularly well-suited for activities like water aerobics or integrating swim jet systems, combining leisure and exercise in a versatile setting.

How Much Does a Small Inground Vinyl Liner Pool Cost?

As of 2025, HomeGuide’s data indicates that the average cost of a vinyl liner inground pool ranges from $16,600 to $49,000 for pools between 200 and 400 square feet, depending on design and features. This price covers installation, excavation, materials, and labor, but excludes additional expenses like decking, landscaping, and optional upgrades such as lighting or heating. It’s also important to consider that vinyl liners typically need replacement every 5 to 15 years, at a cost ranging from $2,000 to $7,500, which adds to the long-term ownership expenses.

How Much Does a Small Inground Gunite (Concrete) Pool Cost?

Gunite (concrete) pools for smaller yards, typically ranging from 200 to 400 square feet, generally cost between $20,000 and $84,000, according to Renotag’s pricing data, depending on the complexity of the design and regional variables. It’s also important to factor in ongoing maintenance costs such as resurfacing, acid washing, and regular upkeep, which add to the overall long-term expense. Taking all these considerations into account will help ensure a comprehensive budget for both installation and long-term care.

How Much Does a Small Inground Fiberglass Pool Cost?

Inground fiberglass pool costs typically begin around an average $2,000 per foot of pool length. For example, the Sea Turtle model, which measures 19.5 feet long, may cost approximately $39,000, while the 27.5-foot-long Lil Bob design can average $55,000 based on this calculation. These estimates generally cover the pool itself but exclude additional expenses such as decking, spa add-ons, and ongoing maintenance.

Unlike vinyl liner or gunite pools, manufacturers prefabricate fiberglass pools in a controlled factory environment and deliver them ready for installation, reducing complexity and installation costs. While customization options are more limited, many features come built into the design, minimizing the need for costly add-ons. Although fiberglass pools generally require less maintenance than other types, regular care—including cleaning, chemical treatments, and electricity—remains essential and should be in your budget.

Plunge Pools

Plunge pools offer a peaceful, space-saving retreat ideal for repose, light exercise, and socializing, with several popular designs that bring comfort and style to smaller backyards.

The Nook
Compact and serene, The Nook measures 8 feet, 4 inches, wide by 16 feet long and features a consistent flat-bottom surface. It’s ideal for lounging or cooling off on warm days. Its simple yet practical design makes it easy to maintain and a perfect escape for calm moments.

The Pearl
With a wraparound bench and built-in tanning ledge, the Pearl brings a spa-like experience to your backyard. Measuring 15 feet wide by 25 feet long, it’s designed for elegant ease and effortless conversation. The graceful curves of this pool create a welcoming atmosphere for entertaining guests or unwinding solo.

Sea Turtle
The Sea Turtle combines style with usability, measuring 9.5 feet wide by 19.5 feet long and featuring generous bench seating and wide entry steps. It’s great for socializing or adding a swim jet for light exercise, and the design adds a touch of sophistication while maximizing comfort.

The Nest
Minimalist in design yet big on comfort, The Nest measures 16 feet long by 8 feet, 4 inches, wide with a flat-bottom surface. It’s easy to navigate, safe for all ages, and ideal for socializing or light water aerobics. Auto-cover compatibility makes it a smart, versatile choice for any backyard.

Other Small Pool Options

These small pool designs provide more room to move while still maintaining a compact footprint. They’re ideal for families, entertaining, or light exercise.

Lil Bob
Designed with versatility in mind, Lil Bob measures 13.5 feet wide by 27.5 feet long and has full-length benches on both sides. The center swim lane supports low-impact fitness and fun. Its practical layout offers ample space for both relaxation and activity, balancing usability with style.

Titus
Titus brings a touch of playful sophistication with its flowing, freeform shape. At 12 feet wide by 26 feet long, it’s perfect for water aerobics, casual swimming, or lounging on the built-in beverage bench. The sinuous design softens your backyard space, making it feel inviting and dynamic.

Aspen (Small Size)
Aspen offers spa-inspired comfort in a space-conscious design. The smallest model measures 12 feet wide by 25 feet long, featuring a spacious tanning ledge, comfortable bench seating, and a courtesy ledge around the deep end for standing and socializing. Its graceful form and thoughtful details provide a serene retreat that enhances any outdoor living area.

Designed for Small Spaces, Built for Big Enjoyment

Whether you’re dreaming of a private plunge pool or a compact design with room to move, Thursday Pools’ small fiberglass models offer smart design, lasting quality, and low-maintenance appeal perfect for maximizing your outdoor space. While the pricing estimates above provide a helpful starting point, connect with a local pool builder to get an accurate quote based on your specific needs. You can also explore options with the free Thursday Pools Pool Cost Calculator. Whichever model you choose, a small fiberglass pool can turn your backyard into a personal retreat.

Pool Specifications

How Much Does an Inground Pool Cost?