my largest s/w set up was 75 gallons, but like i said, that was over 20 years ago. a lot of the rules have changed since then. but there are a few former reefers on here that may be able to help.

waterfalls are what you make them. design it to be easy and it will be, design it to be complex and it will be a nightmare in the long run.....LOL i'm not sure if the crabs would "enjoy" the running water, but it probably wouldn't hurt.