I put clones in a top drip system before I transfer them to flower in RDWC...I have the timer running 3 times in a 24 hours period, for 30 minutes each time...So pretty much every 8-ish hours, twice during lights on, once at night. Clones push roots through 4" net pots in about 3 days, and I have the rapid rooters/rockwool starters in the middle of the pots suspended in hydroton.