https://co2coalition.org/wp-content/uploads/2021/11/2015-Coh...

It states in summary that:

"doubling atmospheric CO2 from the current level of 400 ppm to 800 ppm only decreases the pH of ocean water from about 8.2 to 7.9. This is well within the day-night fluctuations that already occur because of photosynthesis by plankton"

"doubling atmospheric CO2 from the current level of 400 ppm to 800 ppm only decreases the carbonate-ion concentration, [CO2−3], by about 30%. Ocean surface waters are already supersaturated by several hundred per cent for formation of CaCO3 crystals from Ca2+ and CO2−3. So scare stories about dissolving carbonate shells are nonsense."

"Over most of the Phanerozoic, the past 550 million years, CO2 concentrations in the atmosphere have been measured in thousands of parts per million, and life flourished in both the oceans and on land. This is hardly surprising, given the relative insensitivity of ocean pH to large changes in CO2 concentrations that we have discussed above, and given the fact that the pH changes that do occur are small compared to the natural variations of ocean pH in space and time"

"This minimalist discussion already shows how hard it is to scare informed people with ocean acidification, but, alas, many people are not informed."

If you or anyone else thinks this paper's calculations are wrong, then that would be interesting to learn why.