Unfortunately, I don't have time today, but if someone really wants to dig into this idea, we have some data.
Ron shows the relative amount of potassium and other chemicals in both foods and algae (and soft corals) in these articles:
http://www.reefkeeping.com/issues/20...ture/index.php
http://web.archive.org/web/200107200...data/foods.asp
So if we look carefully at the relative amount of potassium in these samples, relative to nitrogen, phosphorus, sodium, etc, we can get a handle on whether foods have relatively more or less potassium than do corals and algae.