Typhoon wrote:
What if it does? What if the process is not harmful, or even beneficial, then what's the problem?
Harmful or beneficial is relative to which species you are.
Having said that, there are two speculative concerns: stimulating toxic algal blooms and depleting oxygen from the mid-level ocean.
I'm sure that there are better uses for iron sulphates.
It could be attractive to invader species.
Men often oppose a thing merely because they have had no agency in planning it, or because it may have been planned by those whom they dislike.
-Alexander Hamilton