Not all rock is conducive for use as a live rock source. You would think that if you just picked up some rocks or stones and put them in a tank they would grow stuff on them. Not so! We discovered this ourselves from our own experience of trying to propagate zoanthid rocks. We tried some red cinder rocks and a certain type of black lava rock, and found that nothing would grow on either one. We figured because these rock sources were so porous and lightweight, and we had picked them up off the beach shoreline, they would do very well. Nope! They just sat in our tank for months and not one thing grew on them. We then took some clean stones, of the same type that our original zoanthid colonies were growing on when we collected them, placing them along side our established stones in the tank and the zoanthid began to populate the clean stones in no time at all. We found that the zoanthid liked dead coral tallus as well. Ah, calcium! As you can see, just any old rock won't do!
Once again consulting with Richard Londeree of Tampa Bay Saltwater, we asked him what he had learned about rock grades, and if there was any particular type that was better than others for propagating live rock. Read Richard's reply to our question, where he explains what they found to work best for aquaculturing their ocean grown live rock, after trying many different sources.
When it comes to making your own base rocks for use in propagating it as live rock, the key to success appears to be choosing the right "grade" of base rock, as well as types of sand and gravel that are conducive to the growth of marine life. Aragonite based materials are best for this. We do know that people have tried using concrete, but not just any old type will do. Most concrete mixes contain other elements that you don't want, and these unwanted contaminates can leach out into the aquarium water over time. As Richard stated in his email reply to us, they too tried this and were concerned about this problem, discontinuing their testing of concrete made rocks for this reason. Another type is what GARF calls their trademark sand molded Aragocrete live rocks, which are made from a combination of CaribSea aragonite gravel and #3 Portland cement. These are just a few DIY plans, but you can find more under our DIY Live Rock & Sand Project Resources.
Before you start cultivating your newly made rocks, you should take the time to learn about live rock and how to take care of it first.
More Articles About Live Rock:
What Is Live Rock? Why Is It Used In Saltwater Aquariums?
Curing Live Rock
Guidelines For Working With Live Rock
How To Cure Live Rock
Tips For Buying Live Rock Locally or Online
Rock Grades and Making Your Own Live Rock