Coral will due fine with the ocean becoming minutely less base. Coral evolved when CO2 was an order of magnitude higher than current levels, and thrived during the Eemian 130k years ago when temperatures were higher than current. Coral also has low generation times and rocks an extremely R selected reproduction strategy which means it's one of the least likely species to be adversely affected by changing climate.
The ignorance chemistry, biology, and natural history required to fall for the histrionics of climate change/global warming is ill becoming of nerds. It requires a serious hatred of the biosphere to work against raising CO2 to the plant friendly 1500ppm utilized in greenhouses and marijuana growing basements. I'll give you the benefit of the doubt and assume ignorance is your excuse.