Looks good but I would recommend making the bottom rocks out of concrete. They will eventually break loose from the bottom if you keep the tank up running long enough. I did some similar rocks by sculpting quickcrete into similar shapes then you can just paint it with the drylok to match.
This has to be the best DIY background/scape I've seen, my favorite at least. Amazing job on this!
How long will this type of thing last? I'm debating making one for a 180 gallon but I don't want to go to the trouble if it's gonna break down in a few months.