That's the million dollar question :lol:
kmacartney nailed it
From what I understand, dosing with Vitamin C is another form of carbon dosing. Some people think that it is beneficial to zoas.
I think most of the science people agree it is just another form of carbon dosing. How/why it seems especially beneficial to zoas is unknown. I haven't followed it much since last winter but I've read most of the 3 split thread
I have no life.
I also never bothered to try it since the science behind it was lacking.
The carbon is doing it by feeding bacteria which lowers phosphates and nitrates
Yep.
Then the bacteria feed phytoplankton which in turn feed your corals. The excess is skimmed out.
I believe your supposed to get increased colors from the coral and increased growth
Sorta
The usual "goal" is to promote a low nutrient system (I think they refer to it now as ULNS). This can cause SPS to turn a pastel color. To help them retain the best coloration it's recommended you either feed much heavier or stock a higher bioload than is/was generally recommended for a SPS tank. Of course you're able to feed/stock heavier because you're carbon dosing.
You should see better coral growth because you're feeding their food source (bacteria/phyto).
At least this is/was the theory of carbon dosing...specifically vodka and the blu coral method when I followed the various threads a few years ago. There are some older threads on vodka, zeo and the like that make the Vit C thread seem like Cliff notes
I have dosed vodka in the past and it worked very well. However, it
may have contributed to my tank crashing.
Having said that I'm certainly considering it again in the new tank if needed. It's much better understood/accepted and the methodology has improved in the past three years. I'm slowly catching up on the more current threads/trends to get back up to speed again.