||03-20-2011 05:13 PM
Basically, it's personal preference. Acrylic is very tough and much lighter-weight. Due to structural weakness, larger acrylic aquaria tend to have more center, edge and/or corner bracing than glass tanks. This bracing, in particular what's called "eurobracing", can make it tough to get off-the-shelf hang on back filters and canister filter intakes to fit properly. Acrylic comes in some wild shapes but does scratch very, very, easily! You can, carefully, drill acrylic if necessary. Over a very long period of time, some older acrylics can yellow. I don't think that's as much of a problem as it use to be.
Tempered glass is heavier and pretty durable, in my opinion, and does not scratch nearly as easily as acrylic. You absolutely can't drill tempered glass! I have both types of tank and like both. I prefer the glass tanks, but the acrylic tank shapes are neat. Pricing for acrylic tends to be higher, but any shipping (if you order versus pick up at local shop) would be less due to weight. Glass aquaria typically will only be shipped by truck (freight), acrylic can be shipped by UPS, etc, depending on size.
NOTE - I think acrylic tanks require support across the entire bottom surface, depending on size (is anyone able to verify this?), not the open metal tank frames often used for glass tanks.