Fish tanks.

[Slow Five-O]

I've done a few. My first saltwater (went from cichlid to saltwater) was a live rock. It was a chore to keep for sure. There was some bad ass stuff in there though at night. Salt water no live rock would probably be a good place to start but I know you do a good bit of reading etc with tanks so I'm sure you would do better than I did with live rock should you choose to go that direction.