I think the only diff i notice from 24/0 and 18/6 was that the stems were a little thicker on 18/6. On 24/0 on the other hand, I would say it grew a little taller.

Chrissy is right, but i still would only do a night period for fresh cut clones or seedlings. I veg my mom's under 24/0 to avoid root bound plants. I don't replant often . . .