Look or one with no cracks, and the silicon that attaches the glass together should be intact.
ooohhhhh...if I didn't have to haul in 55 gallon jugs of water to fill it, I would get rid of the table in my small place......but hope to do 20 this weekend..still looking for the right tank.....Just got a 55 gal for 150 comes with heater filter(even new filters) rocks and minor decore. Oh and Stand