By WaterKeeper
As any manufacturer of acrylic tanks will tell you, acrylic tanks beat glass tanks hands down. Acrylic tanks:
Weigh less than glass
Are stronger than glass
Appear more transparent than glass
Have no seams to leak
Are much easier to drill than glass
Can be molded into unusual shapes
Are better thermal insulators than glass
Help preserve the world’s ever-dwindling supply of silicone
With all these merits, we have barely scratched the surface of the marvels of an acrylic tank. Well, hush my mouth; did I say "scratched"? Sadly, acrylic tanks are scratched more easily than a three-legged horse in the Kentucky Derby; easily enough that this flaw outweighs most of their other positive qualities.
Sure, you say, "I'll be really, really careful," but the sad truth is that even the most carefully managed acrylic tank is going to scratch over time. We all think about major scratches that occur when a piece of live rock is dragged across the acrylic’s surface, but most of the scratching is far more subtle. Particles of fine sand get sucked up by powerheads and propelled into the sides of the tank. Using a magnetic scraper crushes calcium deposits contained in coralline algae into a fine abrasive powder. Kids slide their silver teething rings across the outside of the tank.
Over time, micro scratches in the tank give it a dull, cloudy appearance. One of the main reasons for choosing acrylic is its clarity, and this haze does not enhance that image. Also, the glass aquarium manufacturers are not blind to the fact that standard glass is just not as pleasing to the eye as acrylic. To counter this, they now offer tanks made from low iron float glasses. With brand names such as Starphireâ"žÂ¢, OptiWhiteâ"žÂ¢ and UltraWhiteâ"žÂ¢, these tanks avoid the greenish cast that standard glass imparts due to its iron content. This really levels the playing field.
I've heard mixed results on using buffing kits to remove scratches from acrylic tanks. Some people believe that all they do is trade larger scratches for lots of smaller, micro scratches, creating an overall haze. Touring various threads on Reef Central, you find many acrylic tank owners saying that their next tank will be glass. Not so with glass tank owners, who rarely want to change.
In addition, some of the other arguments against glass are also somewhat overstated. A 100-gallon glass tank, when empty, weighs about 180 lbs., and the acrylic only about 80-85 lbs. Still, when both are full of water, they end up weighing over a half-ton, so a hundred pounds here or there is not a big issue. Glass tanks do have seams, but leakage is unlikely in a quality tank, and usually occurs when you do something foolish, such as trying to move a full tank. The silicone in used glass tanks that have been stored dry can also degrade over time, but they can be repaired. On small tanks, those 20 gallons and under, the acrylic's insulating ability will help to control temperature swings. In larger tanks this effect becomes fairly moot as the water itself provides thermal stability.
True, standard glass tanks are cheap, but if you are considering acrylic, you probably can afford to get a low-iron glass tank. It is worth the extra money and really doesn't cost much more than acrylic.
Overall, I tend to be biased toward glass.
Now, I am sure that some of you will chose acrylic, especially if you plan on an exotically shaped tank. You can't have those with glass tanks. What's that? Well, you tell your glass blower friend to make you a 150-gallon glass tank shaped like the Pillsbury Doughboy, and tell us how it works out. Brother! Anyway, the choice is yours, and I will let you decide.