Question 1, Calcium

[steve-s]

Originally Posted by danny zubot

My question is; do corals actually get used to higher calcium levels and develop a higher appitite for is over time?

Really depends on the coral, it's not a generalized answer. Only scleractinians will be a concern and of those, only "SPS" are really a factor. Euphyllia, Faviids and the like are so slow growing to begin with that elevations above NSW values will not make much of a difference.

When it comes to "SPS' in particular, the problem is they have a specific level that they strive for, loosely being 410-420 ppm to keep equilibrium with their cells. The coral is constantly depositing the Ca it takes in to rid itself of it. When the level of Ca is artificially raised above that, the coral has to work harder to deposit more Ca. In doing so, it cannot easily match the rate of skelatal growth to tissue growth which is where the stress comes in. More commonly a tank running very smoothly will not have much if (m)any issues except for thin reedy growth. Due to the continual stress of the higher Ca, any upset can easily cause a stress event in the coral it would otherwise be able to deal with. If the higher Ca uses up much of it's already low reserves of energy, there's nothing left when a stress event (temp, pH, salinity etc) comes into play.

http://www.findarticles.com/p/articl...02/ai_n8850134

http://jeb.biologists.org/cgi/content/full/205/14/2107

http://www.advancedaquarist.com/issu...2004/media.htm

http://aslo.org/phd/disccrs/200206-4.html

Cheers
Steve