Also scratch when you just look at them.
And are only as good as the materials and craftsmanship used to make them…
You can definitely get very high quality acrylic tanks; though I’ve seen more than I’d like, from major manufacturers, with any number of problems… including but not limited to:
— acrylic used was too thin to prevent immense (>1”) viewing pane bowing, or center brace stress)
— joints were not meticulously prepped and/or were poorly welded… (crazing, bubbles, white haze in welded seams)
— cheap acrylic used (crazing an microcracks in pane faces from years under load, eventually leading to a sudden shattering of the acrylic)
This is before we get into the recent federal ban on one of the primary active ingredients in common welding solvents; Methyl Chloride…
some manufacturers are getting around this with DIY or commercially available two-part welding solvents, but to (roughly) quote a well known acrylic fabricator whom frequents this site:
“I just don’t build anything intended to hold water out of acrylic anymore”