Rock Grades For Propagating Live Rock

Contributed by Richard Londeree
Tampa Bay Saltwater
Dateline: 01/21/98

We obtained test rocks by going to trade shows and getting samples from people who supplied the trade with ornamental rock. We tried rocks from all over the world, keeping in mind the costs involved in shipping it, as to a suitable rock for aquaculture. In fact, I still have a piece of "tuffa" rock in our systems that has been there since 1989. I am sad to report it is still brown, no life has attached and grown, even sitting next to hundreds of pounds of live rock for all these years. This is just an example of a real poor candidate for aquaculture, as were most of the rocks we tested.

We basically tried everything from what the road department uses along our causeways to keep them from eroding, to rock from out west which was of ancient reef origin, but was so hard and mineralized that it too developed minimal growth. We tried rock from North Carolina, a limestone type ancient reef rock, rock from the upland Bahamas, Trinidad, and many other sources. What we found was not encouraging, the growth on these rocks was minimal to nil in our closed systems.

What we did find was rock which had been recently dredged out of the ocean as a harbor and channel widening project in the Islands. This rock was also ancient reef and when cut in half one can see the skeletons of corals, gorgonians, animals and other reef organisms. It is a very porous rock, megascopicaly, and this rock proved to be the prime candidate for use. We imported this rock via ship, where it was off loaded in Tampa, Florida where it was graded for sizes and stored. Then a barge was used to load the rock and transport it off shore to our five acre lease site in the Gulf of Mexico. This rock has now been submerged 5 years and shows astounding marine life growth including five different types of very hardy SPS hard stony  corals, some 2-3 inches in size, plants sponges fan worms tunicates, inverts and much other life. Since the first deposit of rock we have been actively placing new seed rock every trip out to harvest the cultured rock.

We are now using a new rock that is really incredible as it is full of holes, has incredible shapes, is very light weight, and obtainable in many sizes from one pound to 250# pieces for larger personal and public aquariums. This rock has proved to be the favorite of ours and we are actively farming it. This rock is the best rock we have found after a worldwide search and it will be the focus of our attention now.

We have also experimented with concrete blocks and am surprised to find excellent growth on them, but also chemical leaching problems and an unknown time period to eliminate these leaching compounds makes us hesitant to continue in the artificial direction of open ocean live rock aquaculturing. But, with further development concrete may prove viable some day for aquarium use, as it does accrete rather well in the wild. The rock now favored by most live rock farmers is the ancient reef rock." -- Richard Londeree