Correct, in the overall equation of photosynthesis, 6 carbon dioxide and 6 water molecules combine to produce one glucose molecule and 6 oxygen molecules, so there is no net gain of water from photosynthesis. The oxygen is obviously recycled through the process of respiration, which is a net...
Don't think the OP expected the products to "work like on TV"! She states "hard to remove (you can scrape it, but it takes a lot of work lol)". As Mark and I stated above it is best to avoid these commercial products... they are not good for your health, especially if you are asthmatic or have...
Forget the acids and formulaics, just get a new sink :cry: and install a water softener :kiss:. The former will make your sink shine like new and the latter will prevent limescale from accumulating. If you think getting a new sink is expensive and a bit drastic, consider the cost of the daily...