One time in 2018, I had a 220 gallon marineland reef, that we had bought from a dude who had got a puppy from us a few years back. A few days before thanksgiving, the supporting beams going across the tank snapped off! I quickly called the store that had installed it, and was told the following:
"oh, those are just a, uh, precaution that tank makers put on the tanks just for a little extra stability. I wouldn't worry about it, I mean, you COULD replace the plastic rim if you WANT to, but I wouldn't bother. Oh, you say the tank is bowing out? It isn't, trust me."
So me, being naive and not knowing much about refraction, left it, but I did order a new plastic rim for the tank. Two days later, I'm at my brother's house for thanksgiving the next day, and I'm told "oh john, I think your tank cracked. Mom's coming to get you."
So at that point I guess you can fill in the blanks. I didn't have any fish,so that was good, but I lost almost 4 square feet of chili pepper monti, not to mention a whole ton of snails. I told my LFS about what happened and everyone was like, "they told you WHAT?!"
We got a new tank installed for free(we still bought the tank though), and at this point it is a thriving reef.
So I guess what I'm embarrassed about is that I didn't check to see if the stand was level (which it wasn't).
Sooo... Don't buy tanks from craigslist ad have an LFS you don't know install it!