If I grabbed a chunk of Chaeto, what is the best way of growing it, if not in an aquarium? Does it need flow, sun light, co2, or ferts? Does the water need to be warm?
It needs to be under normal conditions for saltwater, any light will do, and it will need rotated from time to time so the 'under' side of the ball doesn't die.
use of a small power head is your best bet to keep cheato rotating and water circulated
still water gets stagnant an will stink over time
as for temp as long as it dont get under 50* it will be fine
a cheap clip on light fixture with a 40w bulb would fine