how often do i water

[jmy]

i built a 11 container garden and i am using lecca (round redish-brown rock) for a medium the question i have is how often do i water because i have excellent drainage and no fear of nutrient build up because i am not using rockwell cubes on this site it said every 20 to 30 minutes but my hydroponic salesman says start out at 3 times per day but that does not seem enough for i just switched from deep water where the roots were constantly submerged can anyone help i am very confused....jmycap