I didn't see this addressed in the thread, or if it was, I missed it. Since plants seem to have a greater ability to uptake nutrients in the water column over algae, would the same principal hold true in regards to vitamins?
Per Tom Barr, it appears that some plants manufacture specific vitamins, but this isn't a topic I've seen a lot of information on (of course, I haven't known to look either). What vitamins do plants require and in what concentrations (macro or micro)?

Cheers,
Kevin