Supplement or not?

[khai]

I have a successful Opae Ulae tank with nicely growing population.
But after some recent online research I feel quite puzzled as some people suggest that supplementing calcium (corals, shells, calcium containing food) is necessary for molting and growth of the colony.

I always assumed, that Opae are able to get the calcium from salt in a brackish water and no further supplementation is necessary. And I'm not very keen on messing with my stable tank.

What is your experience? Do Opae really need calcium supplementation? (let's not consider other potential benefits like buffering and as a side note I do not have snails in the tank)

[KenCotigirl]

I do not know the science but people grow them in tanks with lava only and are successful. So i would say the calcium may not be necessary for moulting.

Ken

[Mustafa]

You don't need calcium supplements in the food or water column, but you do need *calcium carbonate* rocks in the tank in the long run to buffer alkalinity which gets eaten up all kinds of biological processes in the tank including the nitrification process. Otherwise you may one day find your shrimp not so happy because their pH dipped below 7 going acidic. It may take a long time, but it *will* happen.