Free CALCIUM???

yep, oh well, guess thats why i always hated chemistry, not good at it! Talked to my brother in law(BTW wait till ya see what apple is coming out with, his plant just awarded the contract for the plastic for it, cool stuff!) anyways he came up with a plan, then i showed him a calcium reactor and it was a blend of the 2! More natural this way, but less effective! he's gonna look at it a little more, but doesn't see be able to get it cost efficient! Mikejrice, you were right!

 

I agree...

I can't imagine a cucumber or even a few cucumbers producing enough to support the need for calcium in any tank. Not saying it couldn't help though.

 

Interesting thoughts.
I believe the use of a cucumber would take a great deal of cucumbers to amount to the needs of the average coral tank SPS or LPS.
As for the crushed oyster shells, the carbon would remained trapped in a unusable form unless dissolved. Crushed oyster shells are no different that the aggregate used in CA reactors. This requires the lowering of PH to release the CA in a usable form.
There are many ways to combat the negative effects of low PH. the easiest way is to simply run the effuent of your CA reactor through a second chamber. This naturally returns the CA to a normal level.
The secondary bonus to a CA reactor is increase in ALK and trace elements needed in your tank

 

Well, for some reason, researchers are under the conclusion that cucumbers account for half of all calcium carbonate production in the oceans. I know there's a whole lot of sand substrate out there, so that may allow for a whole lot of the little guys in the wild than any one of us can support in one tank. I have been told not to have more than one per tank since one will out eat the other. (I just bought one after reading into this theory) If it is legit, that's one less thing I have to worry about, if not, at least it diversifies my tank.