This is my first time trying hydro, I'm using the general organics, pH testing kit and the flora series. No ppm I just change the nutes once a week and top off with fresh water. Original Amnesia Auto Deep Water Culture - YouTube
Agreed. I would be lost without it. You need to know how much nutes your plants are getting. Really, not according to the nute supplier. They will consistently tell you that you need more. I'm doing my first DWC myself and I definitely would have been lost without it.