Base Rock All The Way

Doing your own rock is pretty cool but if your just going to buy i would recomend any of the sites already mentioned. I have only dealt with marcorocks, it is very good rock to start out with. check around some local fish stores too, you never know what you might find, just look for rock like they have on the sites.

 

And, you can make it even more porous by stirring in pieces of dry ice after the mix is all ready. It creates cavities of whatever size you make the pieces.
A large piece will make a great cave with just a small opening for smaller livestock wanting refuge from larger.
Some people put in macaroni but that takes too long to decay out IMO, and if any remains when you start using the rock it will fuel the algae as the remainder of macaroni breaks down completely.

 

Get reef cleaners its amazing