One thing i would keep in mind, lots of people, me included have enjoyed a lot of success using DWC. There is nothing wrong with that particular system. I have never used GH 3part, but i understand a lot of people have used it successfully. The problem seems to me to be operator error. If you want to do things the right way, i would recommend getting your hands on a EC/TDS meter, and also whatever it is you use to measure humidity. Humidity is often overlooked, and without a meter your really just guessing. Do the plants get watered from the top at all?