Acrylic vs Glass Aquarium: Pros and Cons

There are two main materials that we see aquariums made of, acrylic and glass. Both offer some benefits and drawbacks compared to the other and it’s important to make sure you have the right aquarium for your home. It just takes a bit of knowledge and a frank assessment of your personal situation.

So let’s give you that knowledge! Read on for an overview of acrylic versus glass aquariums!

fish tank

An Overview of Glass Aquariums

Glass is the most common material used for aquariums and the one that most of us know. Glass is frequently encountered in daily life, in everything from windows to the screens that we spend time looking at. It seems a natural choice since it has high clarity and is a very durable material.

Glass is actually a rather strong material, but the form that we normally see it in makes it seem much more fragile. We usually encounter relatively thin panes with a large surface area, making it an easy-to-break material associated with fragility. More robust constructions are quite strong, try breaking a fist-sized chunk of slag glass some time.

Glass’ main drawback is this fragility, especially in smaller tanks. Anything under ¼” will break easily and even thicker panes will sometimes break all too easily due to the water pressure backing them. Any heavy impact will be the end of a glass aquarium.

Glass is also a lot more dangerous once broken, which is a major issue with children and pets. Immediate cleanup is required to prevent someone getting hurt in addition to preventing water damage.

On the other hand, glass is also quite easy to clean. Even hard water stains can be removed from it quickly and easily with virtually anything at hand. I’m fond of using razor blades to line up the edge of tanks where evaporation leaves behind deposits. I’ve yet to scratch a glass tank doing so.

Glass has the strange contradiction of being more fragile but also longer lasting than acrylic.

The long-lasting part comes from the fact that glass isn’t easily scratched. Depending on the glass itself it’s either impossible or very hard to scratch glass with any steel short of a hardened knife or tool. A simple razor blade, or even the occasional brass brush, won’t make a difference to the surface.

That’s a pretty big bonus for those who are careful around their tanks.

Glass is a heavier material than acrylic but the bulk of a tank’s weight comes from the water, rocks, and substrate. It may be a consideration if you have multiple flights of stairs in between your car and the location of the tank.

Glass tanks tend to be cheaper for comparative sizes at the hobbyist level. Acrylic is actually the cheaper material when you get into very large custom tanks but that’s a decision made by a professional designer rather than the hobbyist in most cases.

Glass also has the distinction of being pretty much inert, chemically speaking. Nothing that goes into a fish tank will affect your glass in any way, and it’s non-porous which also removes the absorption issue.

Glass aquariums don’t have much that can be messed up by the manufacturer without a catastrophic failure. The quality isn’t very variable when it comes to construction, at least with commercial tanks. The worst thing you’ll find in a glass tank that still holds water is sloppy seams with too much silicone adhesive used.

The final main advantage is that glass aquariums aren’t affected by UV radiation, unlike acrylic ones.

Pros of Glass Aquariums

  • Very durable to scratches
  • Cheaper for normal sizes
  • Chemically inert
  • Non-porous

Cons of Glass Aquariums

  • Fragile material to impact
  • Heavier than acrylic
  • Shapes other than flat panes are expensive

An Overview of Acrylic Aquariums

Acrylic is relatively new to the aquarium scene but it has some advantages that make it stand out for certain uses.

The first is its impact resistance. An errant coffee cup or erratic pet won’t break acrylic by hitting it. Indeed, acrylic absorbs impact better than most materials and you’d be hard pressed to shatter a panel unless you were actually trying to break the tank.

Acrylic is a plastic compound that’s part of the group known as PMMAs. These engineered plastics are very strong and pretty much designed as a glass replacement. Plastics have a bad reputation, we tend to assume things made out of them are cheap but that’s not the case when comparing them to glass.

For instance, the window bays in most professional aquariums are made of acrylic instead of glass. While some smaller tanks may still be made of glass, the large ones are almost universally made of acrylic. For instance, the monumental kelp forest in the Monterey Bay Aquarium has panels designed of acrylic over a foot thick!

Acrylics’ main feature is always going to be impact resistance. If you have small kids or energetic pets, acrylic is a welcome feature in a tank, preventing the usual mishaps of life from spilling a few hundred gallons of water in your home.

Acrylic also has higher clarity than glass. This is somewhat offset by the fact that acrylic produces a small amount of distortion while you’re looking through it and it will “cloud” over time as micro-scratches build up on the exterior.

Acrylic tanks have more shapes available. Curved glass panes are a specialized product, but curved acrylic panes can be produced in any shop capable of handling the material with ease. The tank may even be a single piece of acrylic, instead of having panes!

The softer nature of acrylic tanks means that you need to take some care when you’re cleaning them. The best acrylics have a similar scratch resistance to glass but they’re not used as often as people would like since they have to be modified chemically.

The main downside, in my opinion, is that acrylic tanks don’t last as long as glass ones if they’re not subject to impact. Acrylic is a strong material but it will break down in a couple of ways.

Cloudy acrylic tanks are usually covered in micro-scratches. Acrylic is about a 4 on the Moh’s scale, which means it’s just a bit harder than copper. Anything harder can produce a scratch, from a wire brush to just the steel rivets on a pair of jeans.

There are ways to remove them but it’s not as easy as wiping down a glass tank’s surface with a damp rag. That said, it’s still easier than removing scratches from a glass tank… it just happens more often.

Acrylic can also absorb compounds into the pores of the plastic, which are impossible to remove. Keeping your water clean remains a very high priority, and topping off your tank regularly with distilled water will prevent small amounts of calcium buildup from penetrating the surface and causing permanent stains.

Even if you keep them from clouding, acrylic tanks don’t do well with sunlight. Direct sunlight will turn them yellow and they’ll still begin to get yellow and brittle over the course of years in any room that allows sunlight in. It takes a long time, but it’s not a problem you have to worry about with glass.

Acrylic is also more expensive for most home-sized tanks. Anyone who has worked with acrylic or resin will tell you that it’s not a cheap material to work with, and a tank can use quite a bit of it.

Acrylic tanks also require a bit more skill in fabrication. You not only have to cut perfect seams and make sure both the interior and exterior are polished, but you also have to ensure that no bubbles are trapped while the acrylic cures.

Because of those facts, you need to be more careful about picking an acrylic tank. While smaller tanks (ie: under 10 gallons) are usually fine, larger tanks leave a lot of possibilities for manufacturing defects. In other words, quality varies a lot more when you’re looking into using an acrylic aquarium. 

Pros of Acrylic Aquariums

  • Better clarity
  • High impact resistance
  • Lightweight
  • Curved panels are more readily available

Cons of Acrylic Aquariums

  • More expensive
  • Scratches easier than glass
  • Yellows over time, especially from UV light

How Do I Pick an Acrylic vs. Glass Aquarium?

Figuring out which of these tanks will work for you depends largely on your own personal circumstances. I’ll admit to bias: I prefer glass over acrylic for every application but extremely large (>1000 gallons) tanks.

That said, that has as much to do with my situation as it does anything else. I only have cats in the home, no children or dogs, so I’m more concerned about a secure hood than I am with impact to the sides of my tanks.

Assess your personal situation, with safety being the foremost concern. If you have small children or medium to large dogs in the home I recommend simply going with acrylic. 

Children, in particular, are one of the biggest hazards for a tank to weather. Loose toys, rambunctious behavior, things happen but one of them doesn’t have to be your aquarium breaking. Of course, tanks in public spaces with unknown hazards are also a preferred application for acrylic tanks.

One final place acrylic shines: if you live up a few flights of stairs then acrylic is often easier to maneuver and carry an acrylic aquarium, especially by yourself. You should check to make sure your floor can support the size of tank you’re wanting but acrylic does make things easier when a tank has to be moved through tight areas.

Glass is preferred for display tanks in private homes without any dangerous variables. They provide a better view of the tank and end up being quite a bit cheaper for the same amount of gallons. The lack of distortion is important for things like heavily planted show tanks, where the clarity of the glass can be a major factor in how good the overall tank looks.

Of course, it’s not like a glass tank is going to shatter the moment it gets looked at wrong. It’s still a fairly resilient material and plenty of fish tanks have survived through homes with children and animals.

If you’re looking for the clarity of acrylic with glass you’re not out of options either. You can get the extra clarity without the distortion by opting for a low-iron glass. If you look at a pane of glass you’ll see that it turns green when viewed on edge, this is due to iron included in the glass. Low iron glass has better clarity, remaining clear even when viewed on end. 

So, to pick the right choice for your home the best thing to do is ask yourself some questions:

  • Are there any dangers to the tank in my home?
  • How far will I have to transport the tank to get it to its final location?
  • How many people will be interacting with this tank?
  • How important are small details to the display of the tank?
  • Do I want a unique shape?
  • Can my floor support the tank?
  • How do I feel about removing scratches on a regular basis?
  • What’s my budget?

With all of these answered you’ll be able to make the right choice for your unique situation. The right answer is, unfortunately, complicated but choosing correctly is very important.

A Personal Choice

Picking the right tank type for your home is mostly a function of the external environment of the home. Taking it into account can save future headaches, and it’s a decision that has to be made early on when you’re designing a new tank. Comparing acrylic versus glass aquariums takes a bit of thought but it’s rather easy. With no overall best option it boils down to your own personal choice.

So, what material are you planning to get for your next aquarium?