Ive heard that 18/6 is better to give your plants a rest and to grow the roots at night. But 24 hours constantly has better veg growth. which is better?
This is an ongoing debate that will not be settled here. Both 24/0 and 18/6 work well (as do 20/4 or other "in between" ideas). The only debate is which is slightly better.
I do 20-4. I turn off at sunset and turn on around 11-12am and I have never had any problems. Plants don't need that much rest until they start getting later in veg.