will reduce precipitation, won't stop ocean acidification
RealClimate covered the precipitation problem with sulfates:
http://www.realclimate.org/index.php/archives/2008/08/climate-change-methadone/
Shouldn't matter if you're using different particle types - it's not a chemical issue, it's a matter of light reaching the surface.
Also ocean acidification will continue until we stop adding CO2, even if we balance out the warming by other means.