Short answer: it is possible, but it is harder than using a mineral hydroponic nutrient and it fails more often. Organic fertilizers depend on microbes to release their nutrients, and in a still Kratky container that microbial activity can use up oxygen and cause...
Short answer: because calcium reacts with phosphates and sulfates when they are concentrated together. The reaction forms solids that settle to the bottom of the bottle, and the plant can no longer use those nutrients. Keeping them in separate bottles prevents it....
