Ehhh lol… i mean both tanks are pretty much in the same boat here… luckily there not that large to really blow a seam for being unlevel and not properly supported. IME ive abused smaller acrylic tanks more so than large ones for temporary quarantine setups and sumps. Sumps are only half full at most tho also.
Best advice i can offer is to not do this for long. Saving space is an easy fix… remove the left stand and build a 2x4 stand for both tanks that properly supports the bottoms. Obvious answer i know. Ive been there before with limited materials, time and $$… Ive set up 55 gals on milk crates in a pinch… no guarantee on how long these will last or pose a problem tho. Id wager the right tank fails first with the gap in the bottom middle. At the least… drain it and place shims in the middle where its sagging between the board and furniture top or fill that lip void entirely with something to level it.
Sadly… these both may be better/safer just right on ur floor if you have too. Not fun to look at that way but it would eliminate the worry of failure. Your boards are long/wide enough on both tanks. Cinder blocks would be the easiest to raise them up on without any building/tools.
