You need 2x4s between the upper and lower frames inside the corners you have built on that stand. Whatever fasteners your yousing will almost always sheer trying to hold that kind of load without any true supports between the upper and lower frames. Good luck on the repairs!great news!!! gonna be a busy day ;Facepalm yes i figured was strong enough only half full ,add supports when adding tubguess notrock back in boxes,drain ,weld tank ,repair stand ,refill,then put rock in...glad had a good day of rest