The researchers have found, that high CO2 levels affect the calcification of SPS corals significantly. Ok – that is what we already know. But soft corals like sacrophyton elegans can cope much better with slightely higher CO2 levels (which also means a lower pH value.)
The researchers explain this by the fact that the tissue of the soft coral is protective and they also have less calcium material than hard corals.
It shows that in zones with high CO2 concentrations in the sea such as in Japanese volcanic island Iwotorishma significantly less SPS and rather soft and leather corals occur. Transfered to a long-term ocean acidification, that could mean a shift of the species richness.
We aquarists use this principle: In a calcium reactor, CO2 is used to lower the pH in the reactor.
Finally, this low pH value dissolves Calcium out of the dead corals. The Calcium-saturated water is used to compensate the calcium consumption of the corals in our tanks.
At this low pH value is achieved, and finally calcium into the basin taken to compensate for the consumption of the calcium corals.