Since this thread is getting some more attention:
Ive heard the "100 year" example several times now. In response to this I say: please show me an acrylic tank that has held water for 100 years. If not, show me one that's lasted 75 years. 50 years? 40? 30? I doubt we will see one. Because it doesnt exist. If it does, its scratched to hell and looks like dogs butt. But acrylic can be reconditioned---BUT---so can glass...
Acrylic is lighter, but you need thicker acrylic when compared to glass ime. If you use substandard acrylic, you will get bowing and your seams or panels will fail, be it 6 months or 10 years down the road.
compare the weight of 3/4" glass to 1-1/4"+ acrylic, and the difference is negligible. In reality, a large tank made from either is equally "friggin heavy" and requires the proper methods and equipment to move safely and efficiently.
As for clarity....the clarity issue is for two types of people: overtly analytical OCD people and acrylic tank sellers. Personally, I will not appreciate my fish any more seen under 99% clarity vs. 85%. I've never thought once that any of my fish appeared slightly too green for my liking when looking through glass.
As to the above statement about a 30" wolf breaking a 3/4" glass panel, I am skeptical. As a missourian would say, you'll have to show me.
It is true that with monster sized tanks, acrylic has the edge because thick acrylic is much more readily available than glass, but it must be known that there are manufacturers that make low iron glass in incredible thickness (1-1/2"+), albeit at exorbitant expense and weight.
And lastly, the seams failing issue. In my personal experience, I cannot claim a winner here. Tanks fail for many reasons, chiefly amongst them user error. I suspect that 90+% of sudden seam failures in both acrylic and glass tanks are due to oversight or accidents by the tanks owner, whether that be in aquascaping, maintenance, or improper setup. The other 10% are just the lemons of both varieties. Like I said, just my theory.
Anyways, the whole thing boils down to personal preference imo.
