This is our 46 bow front ( please forgive the hair algae). You are looking at Agarocrete ( with the exception of a couple small pieces that corals are attached to). I make my own and it is a variation of the Garf method. I use one part cement to two part aggregate. The key to getting it porous is controlling how wet the mixture is.
I use my RO/DI waste water to cure my rock. It take 3 to 6 weeks to cure it this way. I place it into one of my sumps for 2 to 3 months to infuse it ( make it live rock ).
If you have any question, give me a yell.
Ken
PS: Make sure it is properly cured be for you use it or you will have pH problems.