How many times (minimal) a day do you have flood and drain your growing medium (clay pebbles) for a succesful grow? Also how long should you allowing for flooding before you begin to drain the system? Any help would be good.

Cheers

during the veg cycle I have lights on for 18 hours I usually water 4 times a day and only for 15 minutes-or as long as it takes to fill the pots. During flowering when I lower the lights to 12 hours I water 3 times a day