1 1/2 inch is a pretty high wave... I think the warning is a CYA from Tunze. I've sent them an e-mail asking before I got mine. They indicated that 2 tanks have failed based on their experience. One was a really old tank and the other is a DIY tank.
With a 110 G tank, that's 1100 lbs of water alone + rocks, etc. So think about that much water being rocked and how much momentum the stand has to hold for that dynamic weight.
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