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Investigating Acrylic Aquarium Failures

Ultra large aquariums that hold exotic animals are huge attractions at many of the most prominent venues on the planet. People love to get close to aquatic life and walk-through tunnels that make them feel like they are intimately part of the environment.

These aquariums are being manufactured with increasingly complex shapes and are continually getting larger. The material that is making this all possible is poly(methyl methacrylate) or PMMA, also known as acrylic and by a tradename Plexiglas®. This plastic is one of the clearest materials available. Not only is its specific gravity less than half of glass, but the ability to form and bond huge panels together to create massive structures, make it an obvious choice.

Large aquariums in the home or business lobby may hold 500 – 1000 gallons of water. Whereas many public viewing aquariums can hold well over a million gallons of water. Most of these ultra-aquariums have large behind-the-scene rooms that hold monitoring systems, water treatment, temperature controls, and pumps. They also have several smaller, but relatively large, additional aquariums that are used for rehabilitation and nurseries.

Acrylic-based enclosures are not only used to hold aquatic life but are used for holding air-breathing animals at zoos. Acrylic is increasingly being used for deluxe swimming pools where the see-through walls provide an extreme swimming experience.

Though acrylic is the material of choice for these huge, complex structures, it is not immune to failing for various reasons. Unfortunately, because acrylic is relatively brittle, the failure event is typically catastrophic. Because there is so much water involved and the structures themselves are so large, when failure does occur, there is typically a lot of damage during the event. Some causes of an aquarium failure include:

  • Poor manufacturing
  • Introduction of voids or particles
  • Poor materials
  • Molded-in stress (all stresses are additive)
  • Inexact shape or design
  • Improper assembly of panels
  • Preparation of bond surfaces done poorly
  • Bonding done incorrectly
  • Stresses added during assembly
  • Improper installation
  • Aquarium not supported correctly
  • Stresses added to aquarium that were not accounted for
  • Panels exposed to foreign chemicals
  • Structures added to/support by aquarium not accounted for
  • Poor maintenance
  • Improper cleaning chemicals
  • Introduction of scratches or gouges
  • Environment
  • Exposure to unexpected chemicals or stresses
  • Introduction of scratches or gouges

It should be reassuring that most aquariums are designed, manufactured and installed with an extremely large safety factor, i.e. > 10x. Furthermore, many of the manufacturers have been doing this for years. They understand the material behavior, know how to make high quality bonds, know the limits of the material/manufacturing process, and have quality control procedures in place.

large aquarium

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Paul Gramann, PhD, PE

Paul Gramann is one of the founders and current President of The Madison Group. Dr. Gramann received his Ph.D. from the University of Wisconsin – Madison where he served as an adjunct professor within the Mechanical Engineering Department. He is dedicated to design verifications and failure analysis of thermoplastic, elastomeric and thermoset parts. His expert testimony has been invaluable in numerous depositions and trials for both defense and plaintiff counsels.