I have plants in S/H culture using PrimeAgra, and in "normal" culture with bark, CHC, sphagnum, EpiWeb, mounted, and in baskets of charcoal, pumice, PrimeAgra, EpiWeb, or nothing, and they all get fed with the same fertilizer at the dame concentration at the same frequency.
THAT'S why I settled on the 125 ppm N rate (1/2 tsp/gal or 0.65 ml/L of the 20% N formula), as it's a good, general, middle-of-the-road level for my varied collection.
If you want to get more detailed, read my article on
Feeding by Mass