Acrylic Aquariums
Pro and con arguments for using acrylic tanks, common sizes, etc.
If you're going to keep fish in your house, you're going to need to put them someplace! Historically, glass has been used to build aquariums but for the last 50 years, acrylic has become a very popular material for fish tank. This article covers the history of aquariums, pro arguments for using acrylic tanks, con arguments for using acrylic tanks, common sizes, and some useful online sources for you.

History of Fish Tank Materials

While keeping fish for both food and pleasure has been an interest documented starting more than 4,000 years ago, keeping fish in aquariums is a much more recent development. Supposedly Madame Dubarry, a mistress to King Louis XV in France, invented the fish bowl sometime in the mid-1700s. In 1805, Robert Warrington was credited with developing the first sustainable glass aquarium.

During the Victorian period in England and in Europe, fish keeping as a hobby developed quite a following. At that time, hobbyists would use slate or steel bottomed tanks which were heated from underneath with flames! Their tanks were ornate affairs, glass enclosed in steel contraptions that were hardly waterproof. These glass tanks often were "caulked" with a putty to try to help "waterproof" the tank. While continuously improved upon, aquariums didn't really reach a true period of innovation until the mid-1960s when glass framed tanks were replaced with glass sealed tanks. Instead of using metal to frame the tanks, glass aquariums were sealed together using a silicone-based adhesive that made the aquarium water-tight.

Sealed glass aquariums were popular for a decade or so until in the early 1970s, acrylic tanks were being offered to the public. These tanks rapidly became popular because they were lighter and easier to build. For most of the smaller size tanks, you'll find just as many glass tanks as you will acrylic tanks. But as you get into the larger size tanks, you'll find that acrylic is a most popular choice for most people because of its lighter weight when compared to glass.
Pros of Acrylic Tanks

Now that you know the basic history behind the different types of fish tanks you will be better equipped to make a comparison and contrast of the various options. We'll first cover the positive aspects of acrylic tanks. There are many reasons that people prefer acrylic over glass to house their fish – when compared to glass tanks, acrylic tanks are:

  • Lightweight
  • Crack-resistant
  • Easier to cut holes into to accommodate plumbing
  • Better able to provide better views because of curved front corners
  • Available in many interesting molded shapes
  • Better able to provide insulation

In terms of weight, acrylic tanks beat glass tanks hands-down. Acrylic tanks are about half the weight of their glass counterparts. For example, a 20-gallon acrylic tank weighs about 17 pounds, which is about half the weight that a glass tank the same size would weigh.

Another important benefit of acrylic tanks is that they are much more crack-resistant than glass. Some brand name manufacturers even claim that their tanks are 17 times stronger than regular glass tanks. Acrylic tanks will resist knocks and drops much better than a glass tank could ever hope to. Related to that is how much easier acrylic tanks are to cut than glass tanks are. If you want to customize your tank to accommodate plumbing, you'll need special equipment to make cuts in a glass tank. Acrylic tanks are easier to customize which is why they are a popular choice among aquarium hobbyists who build their own sump systems.

Acrylic lends itself to more interesting shapes than glass as well because of the way it can be molded. Besides the regular rectangular shape that we're all accustomed to, you can also find acrylic tanks in hexagons, pentagons, bullets (tanks that are curved on one side and square on the other - they resemble firearm bullets in this fashion), columns, round spheres; the list goes on and on. Some acrylic tanks have a bowed front (curved front corners) which gives an interesting view of the tank from the front. Glass tanks are available in a wide variety of sizes with some being taller than they are long, but the shape options are much more limited with glass than acrylic.

If you're keeping tropical fish, you might be interested to know that acrylic tanks provide better insulation than glass tanks. This may not matter if you have cold water fish but if you're keeping a tropical tank, you probably want to consider this factor. Acrylic tanks can retain heat 20% better than glass tanks which means that your aquarium heater may not have to work so hard in an acrylic tank as it would in a glass tank of the same size. This, however, may not be such a huge plus in reef tanks where you don't want that much insulation (and have more difficulty keeping tanks cool).
Cons of Acrylic Tanks

Although Acrylic tanks have a lot going for them, there's always a flip side! The four largest cons regarding acrylic tanks (versus glass) involve:
  • Higher cost
  • Greater tendency to scratch
  • Chance of changing appearance over time
  • Need for increased support

Probably the biggest con that an acrylic tank will have to newcomers to the fish keeping business is cost. Acrylic aquariums will usually cost more than glass tanks for the same size. For example, your basic 20-gallon acrylic aquarium will run $130 to $140. A basic 20-gallon glass aquarium will run approximately $50. That's a big difference! You might find good deals on smaller tanks or bowls that are acrylic but overall, acrylic tanks will cost you two to three times the price that a glass tank will cost you.

Another issue that can arise with acrylic tanks is that they are easily scratched by cleaning objects or gravel. As long as you're careful when you're cleaning the tank, you should be okay. And just because you scratch a tank doesn't mean you have to scrap everything – a scratch or two won’t make your tank unstable, it will just mar its appearance a little bit. You can buy scratch remover kits that do a pretty good job remedying the blemishes if the appearance becomes an issue for you. Pentair Aquatics makes a popular one - you can buy it for about $23 from Doctors Foster and Smith. Novus Plastic Polishes is another highly recommended one. You can buy it from OceanProAquatics for about $28. The downside to making repairs to your tank is that you'll have to empty your tank to repair the scratches!

Another criticism about acrylic tanks is that they can yellow over time due to exposure to UV lighting. Watch for newer acrylic tanks built with UV stabilizers which are supposed to resist yellowing. Ask the manufacturer for what types of guarantees they may have about the tank yellowing. Tank yellowing may not be a problem for you if you do not expose your tank to direct sunlight, but some aquarium lighting options produce UV lighting so you do need to keep that in mind.

The final criticism regarding acrylic tanks when compared to glass tanks is that acrylic tanks require more support. While technically stronger than glass blow for blow, acrylic tanks will bow under the water weight and need support. Usually acrylic tanks will be encased in support stands which provide extra stability. The top bracing can impede your access within the tank. Glass tanks don't need extra support; they won't bow under pressure. The need for extra supports might be a factor in the increased cost of acrylic versus glass aquariums.

Although there can be plenty to recommend glass aquariums, the fact that acrylic tanks are so much lighter and crack-resistant really make them a more practical choice today, as long as cost is not an issue. Also, with the way that acrylic can be heat molded and still be strong enough to hold water, you'll find acrylic tanks in interesting shapes that you won't find in traditional glass.
Common Sizes

In addition to thinking about what materials you want your aquarium to be made from you also need to think about the size for your tank. When you go to buy your aquarium, you'll need to consider first your living space and the room you have for an aquarium. Most experts will tell you to get the largest aquarium for which you have space and that you can afford. At a minimum, you should go with a 10-gallon tank for a fresh water tank and 20 to 40-gallon tank for a marine aquarium. Contrary to popular belief, larger aquariums are actually easier to maintain than smaller tanks because the higher water volume gives you a higher margin for error. If you make a mistake with water chemistry in a large tank there is more water available to dilute the problem materials so it won’t have as significant an effect on your tank inhabitants as a similar mistake would have in a small tank. Acrylic tanks are available in a wide variety of sizes including the following::

Usually, you'll find acrylic tanks in the following sizes: 10, 20, 25, 29, 55, 75, and 90 gallons. When you pick out your acrylic tank, consider that wider and longer are usually better than taller given the same volume because they provide more surface area (which promotes oxygen exchange - good for your fish). There are, however, exceptions to this rule. For example, angelfish do better in tanks that are taller than they are wide because most of their size is vertical rather than horizontal – they need extra vertical space to accommodate their tall fins.

Special tip: A 55-gallon tank is very popular size, but be careful about the dimensions. You don't want to shortchange your water to air surface area with too large a height to width or length ratio. For example, you'll commonly find that 75-gallon and 90-gallon tanks will have the same exact surface area, even though the 90-gallon tank carries more water. This is another reason to reconsider any "new" molded shapes like the hexagon or column (which are much taller than they are wide). All things being equal you want a tank shape with the greater surface area.

Now that you know the basics about acrylic aquariums, including their pros and cons, you can make the decision for yourself whether you want an acrylic or a glass tank. If you are concerned with durability and stability, or if cost is an issue for you, a glass tank might be the better option. However, if you want something crack-resistant or you are looking for a unique shape, acrylic is the way to go. 

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