Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Well, can you survive on just caffeine? That is energy.
No, you need vitamins, minerals, proteins, carbs, fats...
So do plants have their needs:
N, P, K, C, H, O, Ca, Mg, Fe, and so on (16 elements in all)
The water supplies some of these, depending on its source. You need to supply the rest.