I believe its nitrogen deficiency, as the leaves got stripped of all green, underside slight red/brown tint, but even the veins went yellow. Have treated with epsom salts, as well as some high nitrogen based feed and got my feed to a pH of 6.5. the mildly faded leaves seem to have perked up. The leaves are also limping off, not going crispy as with other deficiency's. I can see the plant dropping one or 2 of the large fanned yellow leaves.