Hey all, ended up putting some wood screws in the sides and some L-brackets on each of the shelves. Also put a cross brace in the back.
Here are the screws in the sides at each shelf. I’m going to put another bit of stain on them tonight, the pic makes it look like they are a lot more noticeable than they actually are.
The following two are shots of the L-Brackets I put on each shelf. I had to use decorative ones on the base of the shelve to hide them. The ones on top are fine because you can't see them unless you look inside the shelf.
Here is a pic of the cross brace I put in the back. It’s a 1x2 piece of wood running from the top corner to the bottom opposite corner.
The finished product! Much sturdier than before.
Bonus pic of the kitty cat who seemed a little too curious with the tank on the floor. Had to keep it there while I was repairing the stand.