The part b in jacks 321 is calcium nitrate and part c is added magnesium so thats how i get calmag, ive been feeding half streght so far tho, the rocks is volcanic rocks that im using as mulch to keep the top layer of the coco from drying to fast and for the cocodust the fan pulls up. I fed full strenght jacks today but ppm came to 140, is that low? Ec 250