I've been doing research on nutrient ratios for use in organic growing - that's my thing right now. There is quite a bit to be understood about the relationship between all of the macronutrients but specifically N-P-K-Ca-Mg-Su, etc. Along the way I ran across this book that I think anyone growing hydro or aero would find extremely beneficial to their pursuits. Particularly true if you are able to meter your ppm's for different nutrients. I ordered a copy through the local library and they got it for me – kewl! You might find some utility from its many references and footnoted sources. Quite scientific, easy to read, and it might cause a paradigm shift in your thinking! Knott's Handbook for Vegetable Growers Donald N. Maynard and George H. Hochmuth, 5th edition. Enjoy.