whoa killer hang on,lots of things are going to make up your answere.1.what kind of media are u using.2 age /general info about the plants. 3 describe the system you have built "it will make a tone of difference in your watering choices,4 what kind of lighting are u using "hps lamps tend to dry our rw much faster than say cfl's" all of these things are factors.most people water 3 times a day in 15 min intervuls,some people only require once or twice,but you will def need to up your water schedule as the plants mature.generally i would use drip nossles to put back pressure on the diaphram head"were all your lines connect 2" to make sure that all of them are producing the same amount of water trust me it will happen.u have 15 lines and 2 of them have nothing coming out"pain in the ass"soooooooo anywhoooo those are the questions that need answering 2 get you the correct answers.