There is a way to make your own nutrients based specifically for type of media used & for specific plant.
A setup of small research scale lab can help prove it.
The essentials nutrients needed are provided online but the issue arises due to amount of individual compounds used.
As each compound is related to individual deficiency the OPTIMUM amounts required can be found out by biological titration of each compound on different plants.
Proper documentation & use of statistical analysis will help setting limits (range) of each compound (for specific plant).
Same conditions should be done simultaneously with another fast growing plant which will determine effects of variation in nutrient with another species. (Determine & set limits for optimum nutrients, so v can use the same formula on other plants without getting it killed).
Help by experts/Professors in analysis would be helpful.
The profit of this is, you have a documented proof & this will help reveal secrets protected by nutrient sol company (trade secrets).
I'm trying for this project, but since its difficult for a student to secure funds & as my ethics are against commercial exploitation, it shall take few extra months but I believe in revealing the information to public. keep visiting this forum. Although a major issue of obtaining profitably purified water is another issue that needs indigenous method application.