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How to Tell if Aquarium Is Glass or Acrylic

If you’re just starting out with fishkeeping, there are numerous elements of the practice you should consider. Dealing with aquatic life takes lots of research and planning to provide them with the best care. One of the most important aspects is the environment, so you must invest in a quality aquarium. This article will help you discover how to tell if aquarium is glass or acrylic and the tips for differentiating these materials.

Many people mistake aquariums for typical fish bowls. But there’s a whole specialty behind crafting these unique tanks. Furthermore, they can be used as a marketing tactic for restaurants, hotels, and luxurious venues. That’s why many professionals put an emphasis on their type.

Continue reading to learn how to differentiate glass from acrylic aquariums and discover which suits your demands best!

How to Tell If Aquarium Is Glass or Acrylic

While most people don’t mind the material an aquarium is made of, choosing the right one can make a world of difference. While the two most popular types are glass and acrylic, many new enthusiasts have a hard time telling them apart. Even experts struggle to guess if they’re acrylic or glass when all they have to rely on is pictures.

However, several characteristics can help differentiate them in real life, including:

  • Material
  • Weight
  • Shape
  • Thickness
  • Light refraction
  • Clarity
  • Support
  • Sustainability
  • Cost


The most obvious difference between acrylic and glass aquariums is the material they’re made of. 

The first type is also known as plexiglass, but you shouldn’t confuse it with real glass. Acrylic aquariums are made from refined plastic or acrylate polymers, also known as acrylic acid polymers. It’s a stiff, clear, and strong plastic with glass-like qualities. While it’s available in many different colors, it still offers transparency, clarity, and brilliance.

On the other hand, glass aquariums are made of natural materials, such as sand, limestone, and soda ash. By melting them at high temperatures, glass forms in a liquid state. When it’s cooled down to room temperature, it solidifies and has refractive and reflective properties. During the creation process, metal salts can be added to color the glass for further aesthetic preference. 

These two materials have different properties, so several unique characteristics are based on the type. Such are weight, thickness, refraction, and clarity. 

Glass vs Acrylic- Material
Source: / Photo Contributor: Jovan Barajevac


With the different compositions of the materials, the second characteristic that can help tell acrylic and glass aquariums apart is their weight. 

Since glass has a higher density, it’s also several times heavier than acrylic. This characteristic is important to know if you’re planning to move your aquarium. Even with the water drained out, the same glass volume can weigh up to 10 times more than acrylic.


Another common difference between these two aquariums is their shape. Glass tanks are very rigid and less flexible, so their shapes are mostly rectangular. Even though there are numerous curved-shaped glass tanks available, their biggest issue is light bending. Because of this property, the objects’ visibility inside the aquarium is distorted, thus appearing smaller or bigger than they are.

Acrylic tanks, on the other hand, can be found in various shapes and sizes. Since they’re easily flexible and have less distortion, they’re ideal for molding the aquarium based on your unique design. This gives you more creative freedom and allows you to create the ideal tank that fits your surroundings best.


Next, you can also check for the aquarium’s thickness. Glass tanks are often thicker than acrylic, which is also why they’re heavier. Even though tempered glass doesn’t need to be as thick as non-tempered, acrylic tanks are still thinner. Another thing to remember is that glass ones can’t be drilled into to customize them further.

When it comes to acrylic aquariums, the material they’re made of doesn’t require much thickness to support the same volume of water as glass ones do. Plus, they can be easily drilled into to apply unique and special features that will set them apart and make them more convenient.

Light refraction

Another difference between acrylic and glass aquariums is their light refraction properties. This comes down to how many times the light is bent, directly affecting how much the objects inside the aquarium are distorted. 

Since glass is thicker and has a higher index of refraction than water, the light bends more. Therefore, the colors, size, and positioning aren’t as precise. 

Acrylic tanks have a similar index of light refraction as water, so the light bends less. This means that the visibility is less distorted and mainly affects the objects’ positioning. As for the color and size, they appear more natural and vivid.

Light refraction
Source: / Photo Contributor: Zyabich


Going hand-in-hand with light refraction and distortion, another different characteristic between these two types is clarity. Glass aquariums have a longer duration and don’t lose their clarity over time. 

However, when it comes to acrylic tanks, one main inconvenience is that their panes start turning yellow as they age. This yellowing process is due to the materials acrylic is made of and their natural chemical reactions with the elements. 

There are several ways to slow down this process, such as avoiding direct sun exposure and using only suitable cleaning chemicals. But even if you maintain the tank regularly, it will still have a yellow tint over time.


When it comes to supporting your aquarium, there is a slight difference between glass and acrylic types. While glass ones have a strong bottom and require only partial support, acrylics have weak bottoms and need full support stands. 

Furthermore, glass aquariums can support more than their weight and don’t need top covers. Acrylics, on the other hand, also require delicate top support to ensure they don’t split apart. When deciding on a support system for your aquarium, always check if it’ll hold the weight to prevent any unwanted damage. 


Even though you’ve bought your aquarium from a professional service, it doesn’t mean that it won’t take damage over time. Based on the durability of the materials, there are several things to note.

First, acrylic tanks have higher durability than glass ones. They’re more impact resistant, so they won’t break as easily as glass. However, acrylic aquariums can scratch more easily. So if you notice lots of little lines on the surface, you’ll know it’s an acrylic type.

Even though glass is less durable, it’s very scratch resistant. You won’t have to worry about damaging your tank with various decorations or during cleaning. 


Last but not least, the biggest difference between glass and acrylic aquariums is their cost. Even though acrylic tanks are lighter and more flexible, they’re still harder to ship than glass ones. That’s one of the main reasons they hold a higher price. Plus, glass aquariums are more common and easily accessed.

Another issue that may arise is damage during shipping. Since acrylic tanks scratch easily, they may take more damage and thus cost more for repairs. 

You might be interested in: Fiberglass fish tanks as a third alternative.

Tips for Differentiating Acrylic and Glass Aquariums

Now that you know how to tell if aquarium is glass or acrylic, there are several methods used to tell them apart in real life. These tips will help you make the right decision when planning on your tank’s duration, sustainability, and overall quality. Here’s what you can do to ensure the material of your aquarium:

  • Tapping – try gently tapping on the aquarium’s surface with a metal object like a ring or coin. By doing so, you can tell the difference based on the sound the tapping makes. If a dull sound comes out, the aquarium is acrylic. On the other hand, glass creates distinguishable high-pitch sounds. 
  • Checking the temperature – the second test you can do is check the aquarium’s warmth by placing your hand on it. While acrylic plastic maintains a warmer temperature, glass is always colder to the touch.
  • Checking for silicone – the last thing you should keep an eye out for is signs of silicone. If you notice that the edges are joined with this material, then the aquarium is made of glass. Acrylic plastic doesn’t require silicone to hold it together. 


After learning how to differentiate between glass and acrylic aquariums, it’s up to you to decide which one you want to invest in. Since they are expensive and require consistent maintenance, getting them from a reliable source is recommended. This way, you’ll know you’re getting quality materials worth your money.

However, if you find yourself in a situation where you have to tell these two aquariums apart yourself, ensure to do so in real life. Since they’re basically indistinguishable in pictures, you’ll have to trust the description when purchasing the product online. In person, you can use the methods we mentioned to ensure you get what you’re paying for.

When learning how to tell if aquarium is glass or acrylic, focus on the weight, thickness, shape, clarity, and cost. By remembering all the specifics mentioned in this article, you’ll have no problem differentiating these two aquarium types!

Neal Moir

Neal Moir

is the owner at Titan Aquatic Exhibits and brings more than a decade in aquarium and acrylic pool wall manufacturing experience.

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