What is the evidence it is feasible to reverse ocean acidification by adding large quantities of a base (bicarb soda)?
Instead of using sodium bicarbonate why not use limestone instead? Limestone is already used on an industrial scale to neutralise acids and acidic solutions. Also, sodium bicarbonate needs to be manufactured, whereas limestone just needs to be dug up. The manufacturing of sodium bicarbonate would unnecessarily use energy and potentially create more carbon dioxide if it were to be used to neutralise the worlds oceans.

Danny Harvey of the University of Toronto has already looked into this. His solution is to deposit 4 Gt/a of limestone into the oceans. To put this in perspective, global coal production in 2013 was nearly double this at 7.823 Gt and it is more than global iron ore production in 2014 of 3.22 Gt. 

The mining of so much limestone would be a massive and expensive undertaking. Then there are the added costs of grinding the limestone to $40 \mu m$, as specified by Danny Harvey. Added to this would be the cost of depositing the finely ground limestone to the oceans. Because the limestone could not be expected to be dumped at one coastal location and then disperse globally, this would require a fleet of ships to deposit the limestone all over the oceans.

The other things to consider include:


Are there sufficient quantities of easily obtainable limestone to do
this?
What would such a use of limestone do to the supply and cost of
cement, used for construction, etc.?
What impact would such a huge annual deposition of limestone have of
ocean life forms and biodiversity?


The other thing that Danny Harvey states in his document is that 4 Gt of limestone would need to be deposited in the oceans annually for at least 200 years for "a modest additional benefit".