How long does it take for a certain amount of Co2, to be absorbed into the ocean? And what is chemically happening?

CO2+H2O -> H2CO3

H2CO3+H2O -> 2H3O+ + CO3(2-)

carbon dioxide dissolves into the water to form hydrogen carbonate, which is slightly acid in water. the process is a slow one, dependent on many factors like concentration in the air, temperature, how much is dissolved in the water already...

depends on factors.

though there is research done that predicts the oceans would not be as good of a carbon sink as first thought, as the warming of the planet would decrease the ability of the CO2 to form H2CO3

its also a bad thing, as increasing acidity in the oceans causes issue. whats already happening is coral is dieing. im not a marine biologist, but id imagine that acidity isn't good for fish.

yep as far as i know, there are some species of coral here that are turning white already

Henry's Law

Carbon dioxide will react further to produce limestone and used by alge and such for the same things.

there is more than the henrys law equilibrium at work in this. there are equilibrium between the dissolved carbon dioxide and carbonates of all forms in the water, and equilibrium between the limestone and carbonate. you could model the behaviour with some effort, but all the conditions change so much in the ocean and atmosphere it would get very complicated very quickly.

Pick up a fucking enviro chem textbook, this has been flogged to death in the research literature.

this is what i thought, slow process and would increase acidity of oceans
but could there be a way to increaes reaction time on a small scale?
like in a fish tank or a water heater size container?

what are you trying to do?