I have a number of questions for you:
- Where did you find these so-called "optimum levels"?
- What are they?
- How were they determined?
- How often must they be applied?
I ask, as I am skeptical of any "ideal" or "optimal" concepts when it comes to plant nutrition, considering the variability of the various cultural parameters among growers, all of which affect nutritional needs.
I also want to know, as I wonder if the data is being interpreted correctly. Let me explain:
The Greencare "Orchid Special for RO" (the original so-called "MSU Formula") is 13-3-15-9Ca-2Mg. For each ppm of applied nitrogen, the solution will contain:
N 1 ppm
P 0.099 ppm
K 0.943 ppm
Ca 0.682 ppm
Mg 0.152 ppm
If we use the 50 ppm Mg as the base for calculations, using this particular formula, to reach that "optimal" 50 ppm Mg level, we would need to apply it at a concentration of 330 ppm N, giving a solution of containing 225 ppm Ca, but with a total of about 1500-1700 ppm TDS - a level likely to be damaging to the plants' roots.
By contrast, I am feeding 25 ppm N K-Lite (a derivative of the MSU RO formula @ 12-1-1-10Ca-3Mg), giving me a TDS of about 100, and in order to match that 50 ppm Mg level, I would have to feed at 215 ppm N. I am seeing no issues with any deficiencies.