Oh right, good call Killa.
Rockwool and Hydroton have different flood schedules. I gave the one for hydroton. It drains out to driness a LOT faster than rockwool does!

What's your medium? Also yout temps and plant size will influence how fast your medium dries out. Some rockwool folks will flood LESS frequently when the plants are small, and then have to flood a little more often as they grow and demand more water.