I'm a first time grower planning a pretty ambitious SoG project (80 sqaure feet). I'm an engineer by trade, and in order to design efficient drip irrigation systems I need to know some numbers.
First, is there any merit to doing a continuous, low flowrate drip instead of a periodic drip schedule? If so, what flowrate (gph) should I use per plant?
Second, is there any merit to having drip cycles during the night hours of the day?
The vegetative room will be on 18/6 days. I was thinking about doing four, 15-minute drip cycles, one every four hours during the daylight, on hours 0, 4, 8, and 12. There will be two independent drip systems (two reserviors, two pumps), but both pumps will be on the same timer. One system feeds the mothers and clones (0-4 weeks) on 1/2-strength nutrients under eight 4-foot T5 HO flourescents. The other feeds the main vegetative plants (4-8 weeks) on full-strength nutrients under 1000W MH.
The plants for these systems will be in one of two media. Young clones (<2 weeks) will be spray-watered manually once per day. Older clones (2-4 weeks) with be in 4" rockwool on a drip tray. I was thinking of using one 1-gph inline pressure-compensating dripper per plant at this stage. This equals 1 quart of solution per plant per feeding, or 1 gallon per day. Is that on the right track?
The mother plants and main vegetative plants (4-8 weeks) will be in 3.5-gallon buckets of clay pebbles with a 1/2" drain in the bottom. I was thinking of using four 1-gph inline pressure-compenstating drippers per plant (arranged neatly around the stem) at this stage, for a gallon of solution per feeding and four gallons per day. Is this too much?
The flowering room is of course 12/12. I was thinking three, 15-minute feed cycles during the daylight at hours 0, 4, and 8. There are two crops of 6 plants running simultaneously in the flowing room, 4 weeks apart, each under its own 1000W HPS. Full-strength nutrients in a single large reservior. The plants are still in 3.5 gallon buckets with clay pebbles, and I'm thinking four 1-gph drippers per plant again. This means 1 gallon per feeding and 3 gallons per day. About right?
I know it's kind of hard to overwater when your dripping through pebbles into a 1/2" drain, but I want some degree of efficiency. Also, I read somewhere that the rule of thumb for reservior size is that it should hold enough solution to run through one day's feeding cycles. This means I need two 24-gallon reserviors in the veg room and one 36-gallon reservior for the flowering room.
Thanks for your help. I'm glad that there's so many resources for first-time growers like me. I'm sure that your experience and my general toolishness will yield great results! Of course I will photodocument my progress here once I begin construction (May 1).