Honestly im still very new to saltwater, i had a 55 gallon aggressive tank for about 5 months, fell in love with this hobby and bought a 125 acrylic tank with all the bells so i could have a really nice reef. I've been reading book after book to learn more and more as well as reading in the fourms, but in instances like this i dont think my advice would be any good, or be proper advice. IMO if your talking about adding ph buffer... im assuming as cloudy as your tank is nothing is currently in it, i would add the buffer directly to the tank myself since its just sand/water. But thats me. I would research before you do it.
What kind of filtration are you running?
lights? etc.
also how many pounds of live rock are you going to add?
~chris