Last week I was wondering if I had a magnesium deficiency or not. The problem was that I've been feeding the plants AN Grow and Bloom which contain the mayor nutrients (NPK), I later found out that I was supposed to use AN Micro at the same time that Grow and Bloom. Yeah noobie mistake as I was not feeding them a lot of nutrients, Micro contains calcium, magnesium, iron, manganese and boron.