1. The fundamental difference
Glass is an amorphous inorganic silicate. Acrylic (PMMA) is a thermoplastic polymer. This chemical difference determines everything.
2. Elasticity (Young’s Modulus)
| Property | Glass | Acrylic (PMMA) |
| Young’s Modulus | ≈70 GPa | ≈3 GPa |
| Behaviour | Extremely rigid | Elastic, flexible |
3. The danger of glass under pressure
Glass has a very high Young’s modulus. It does not bend visibly – but it also cannot handle tension well. Under constant water pressure (pool or aquarium), glass is always stressed very close to its allowable limit.
Consequences:
- Any small impact – a dropped toy, a kicked fin – can cause sudden, catastrophic explosion.
- Glass fragments into large sharp shards (float) or small cubic pieces (tempered). Both can injure.
- No warning signs. No plastic deformation. Just sudden failure.
4. Why acrylic is safe
Acrylic has a low Young’s modulus. It is elastic. Under water pressure, it deflects – but the internal stress remains many times below its allowable limit.
This means:
- Acrylic absorbs impacts without failing.
- It gives visible warning signs (scratching, crazing) before any structural issue.
- In extreme overload, it breaks into large pieces with blunt edges – no dangerous shards.
- It is designed for high safety factors, not for ultimate performance limits.
5. Engineering philosophy: family cars, not Formula 1
When designing products for the public – families, children, schools, hotels – engineers apply very high safety coefficients. We need structural stability, predictability, and long‑term reliability.
Formula 1 engines are powerful but fragile. They fail often (one engine every two races). That is unacceptable for a pool or aquarium.
Ocean Acrylics designs utilitarian‑safe, not F1‑extreme. Reliable. Durable. Guaranteed over time.
6. Conclusion
- Glass in a pool or aquarium is always under tension, always close to failure. It is dangerous.
- Acrylic works safely, with stress far below its limit. It is reliable.
Choose acrylic for public safety. Choose acrylic for peace of mind.
Ocean Acrylics – engineering transparency with high safety factors, proprietary adhesives, and 20+ years of global experience.
info@oceanacrylics.com