Something for nothing??? Could this be??? I've been reading that in nature, over 50 percent of all calcium carbonate is produced from a very simple creature we all know, and even some of us own. Any takers??? It's the Sea Cucumber!!! From the stomachs of these guys acid is produced, which is actually just breaking down the crud around sand these guys eat, but there's also small shell and old coral bits that get eaten too. This, in turn, is supposed to recycle the calcium that's trapped in the old skeletons, and release it into the water. Most large tanks prefer the use of a calcium reactor, which drops the PH in a controlled chamber, freeing calcium and alkalinity ions from added substrate, and dripping them back into the tank. Could this be done naturally simply by adding a Sea Cucumber? And, adversely, there are some people out there that seem to have issues with high calcium and imbalanced Alkalinity levels for no apparent reason. Could these little guys be the unknown culprit? It's worth looking into.