[Flatlander]

Greg; I agree with most. However, I have found the more intense the lights, the lighter the coralline colour.
Under Iwasaki,s its a pink/purple and under normal outputs its a darker, deeper purple. I even grew some maroon under normal bulbs. The darker also seems to love actinic colours, which of course is darker.

Magnesium & strontium, do indeed promote growth, of course with good levels of calcium.

One of the best additives for the growth of coralline is a two part ca/alk. supplement. I have had great success with both ESV & C-Balance.

Toptank, these two part supplements contain magnesium & strontium, along with other trace elements. Thats why they grow coralline well.