What Can Damage a Fiberglass Pool?

 

It’s only natural to want to do as much research as possible before making a significant decision and investment into a major home addition like an inground fiberglass pool. You’ll want to learn and consider details such as installation costs, maintenance responsibilities, and how long it will last. A durable pool shell helps protect your investment, so you’re likely asking questions like, “What can damage a fiberglass pool?” or, “Can you scratch a fiberglass pool?” Worried about fiberglass pool gelcoat problems or bulging walls? Understanding how common fiberglass pool damage can happen can help you prevent it with your pool or know when repairs are necessary.

 

Common Causes of Fiberglass Pool Damage

 

Fiberglass pools are famously durable, but they’re not indestructible. 

 

Structural Stress

Improper installation or soil movement can place uneven pressure on the pool shell, leading to bulging walls or cracks. Professional repair and proper backfilling during installation are essential to restore stability.

 

Sharp or Heavy Objects

Dragging metal, glass, or other sharp items across the surface can scratch the gelcoat finish. Shallow scratches may buff out, but deeper damage may require a gelcoat repair.

 

Improper Draining

Completely draining a fiberglass pool without professional supervision can allow groundwater pressure to push against the shell, causing cracks or shifting. Always work with a qualified installer if your pool needs draining.

 

Harsh Cleaning Tools

Wire brushes, stiff bristles, or metal scrapers can scratch or gouge the gelcoat. Stick with soft cloths, nylon brushes, and fiberglass-safe cleaning products to keep the surface smooth and shining.

 

Extreme Weather

Ground freezing, flooding, or other severe weather events can stress the pool’s structure if it isn’t properly protected. Preventive measures like winter covers and proper water balance help reduce the risk.

 

Pool Water Chemistry

Imbalanced water doesn’t always cause direct visible damage, but it creates conditions that accelerate staining, scaling, or gelcoat deterioration. Keeping water properly balanced protects your pool’s beauty and performance for years.

 

How Does Fiberglass Pool Chemistry Protect Against Pool Damage?

 

Water chemistry can be tricky for pool owners to master, but understanding how it works and best practices can help ensure the best preventative care possible for your pool shell. Fiberglass pool shells developing discoloration and turning a chalky white is often a result of a water chemistry imbalance. 

 

Fiberglass pool surfaces are very durable, but they are not indestructible. Water balance is vital to ensuring surface finish protection in your fiberglass pool. Balanced pool water is neutral, meaning that the water is neither corrosive nor scaling. 

 

High calcium levels can contribute to rising pH, leading to white deposits and surface discoloration on your fiberglass pool. With elevated calcium and pH levels, the result is often irreversible damage to the gelcoat finish. The good news? It’s also 100% preventable with proper water care.

 

Our fiberglass pool owner’s manual recommends calcium levels remain below 120 parts per million (ppm). Source water can often run above 120 ppm, in which case using a stain and scale control product is imperative. In our experience, Pool Stain Remover’s Scale and Stain Eliminator and Orenda’s SC-1000 do a good job chelating calcium and keeping it from discoloring your pool finish.

 

We recommend keeping chlorine residual levels in your pool between 1 and 3 ppm. Exceeding 5 ppm can damage the pool surface.

 

The pH level, which measures the acidity or basicity of water, should be between 7.2 and 7.4. Total alkalinity measures the amount of bicarbonate material in pool water and indicates the water’s capacity to withstand changes in pH. We recommend total alkalinity levels between 80 and 120 ppm.

 

Finally, cyanuric acid prevents the decomposition of free chlorine in the pool water. As a stabilizer for chlorine, we recommend cyanuric acid levels be between 20 and 50 ppm. As levels rise above 100 ppm, chlorine is not as effective at killing bacteria and algae. 

 

Preventing and Fixing Fiberglass Pool Issues

 

Discoloration and Residue: Regular water testing, maintaining proper water chemistry, and certain equipment add-ons can prevent discoloration and deposits on a fiberglass pool’s surface by suspending calcium and reducing the need for high levels of chlorine. Getting guidance from a local pool maintenance professional is often the best way to address discoloration and residue issues, but homeowners can usually perform effective maintenance methods.

 

Spider Cracks: Fiberglass pool gelcoat repair methods are available to restore the gelcoat after cracking. Your independent pool builder or maintenance professionals will be able to point you in the right direction for obtaining gelcoat repair services.

 

Pool Wall Bulging: Bulging in fiberglass pool walls can happen when groundwater pressure combines with the ground’s natural tendency to shift, but it is often due to incorrect installation practices. The best way to prevent wall bulging is to choose a manufacturer that accounts for both flexibility and rigidity in their pools’ structures. Some innovations, like the Thursday Pools Geo-Anchoring Pool Wall®, provide additional structural support by anchoring the pool to the earth to help prevent bulging or shifting.

 

Prevent Damage and Protect Your Pool

 

We always applaud those who do their research before splashing into the world of fiberglass pool ownership. To learn more about preventing and repairing potential fiberglass pool damage, connect with a local independent Thursday Pools dealer near you.

Fiberglass Pool Damage Frequently Asked Questions

 

1. Can a fiberglass pool crack?

Yes, but it’s uncommon. Cracks usually result from improper installation, soil movement, or draining the pool without professional oversight. Working with expert installers and following proper backfilling and drainage practices minimizes the risk.

2. What causes scratches on a fiberglass pool surface?

Scratches happen when sharp or heavy objects (like metal, glass, or rough brushes) drag across the gelcoat. To protect your finish, always use fiberglass-safe cleaning tools, pool toys, and accessories.

 

3. Is it safe to drain a fiberglass pool?

Not without professional help. Fully draining a fiberglass pool can allow groundwater pressure to push against the shell, leading to cracks or bulging, and it may void your warranty. Always consult a pool professional before lowering the water level in a fiberglass pool.

 

4. How does water chemistry damage fiberglass pools?

Imbalanced water can discolor the gelcoat, cause chalky buildup, or shorten the life of your pool’s finish. Keep pH (7.2–7.4), chlorine (1–3 ppm), calcium hardness (under 120 ppm), and alkalinity (80–120 ppm) within fiberglass-specific ranges to protect your pool.

 

5. What should I do if my fiberglass pool develops discoloration or bulging walls?

Discoloration often improves with proper water balance and stain prevention products. Bulging walls require professional evaluation, but structural innovations like Thursday Pools’ Geo-Anchoring Pool Wall® can help prevent the problem in the first place.