How is the photosynthesis possible under water

How can water plants be able to perform the photosynthesis under water?

I know the formula for the photosynthesis:

6 H2O + 6 CO2 + sunlight → C6H12O6 + 6 O2

But the carbon dioxide that is dissolved into the water reacts with the water molecules according to this formula:
H2O + CO2 → H2CO3.

Videlicet, Carbonic acid. Carbonic acid then reacts: H2CO3 → H+ + HCO3 -
And thus making the water acidic.


So. How is the photosynthesis possible? Does the plant break up the unstable carbonic acid molecule and then uses the carbon dioxide, or does the plant simple devour 6 H2CO3, which is equivalent to 6 H2O + 6 CO2?

That’s a great question but fundamentally photosynthesis actually began in the oceans — in underwater, because that’s where plants and algae first evolved. They then moved onto land. So light definitely gets into the upper layers of the ocean and that’s where the process of photosynthesis traps that light and converts it into energy — into carbohydrates really, that the rest of the food chain relies on. So it’s really the idea is that you have to maintain plant life, algae has to maintain itself in the upper layers of the ocean because once you get further down into the depths of the ocean, first of all red light gets absorbed which is why the oceans look blue and green-y colours. Light does get down there but it has to maintain itself up in the high levels. So if you look, for example, at coral reefs and they have plants living inside their tissues or algae and those types of coral have to maintain themselves by growing on big reefs, depositing calcium carbonate in great big layers that build up and build up and as sea levels rise, they have to keep up their pace to keep themselves in that lovely, sunny, gorgeous bit of tropical oceans where we all love to go snorkelling and diving. But as you go deeper down, they tend to peter out, and there are some types of corals actually that don’t have photosynthetic algae in their tissues; they actually rely on catching their food like other animals. They catch it from the water, and those are the ones that live deeper down. So you do see this zonation. You see similar things on the beach with different types of seaweed using different types of pigments to harness light both in the open areas where there’s lots of light and then lower down where light start to get absorbed.

Dude H2CO3 is a weak acid even if you heat it, it will give back carbon dioxide and water so this reaction is very slow also since it is a weak acid it gives around only 200 molecules per minute thats extremely slow process . If you ever see the process of c3 cycle it shows plants take in both carbon dioxide and water from atmosphere and that to one molecule each . So this means the already got carbon dioxide and water weakely combined from water . So even then c3 cycle will proceed as it got both water molecule and carbon dioxide. I don't think there is any problem with this in plants . And rest of process take place in organelle called chloroplast