A very good idea for us all to think about the chemistry of things.

Here is a related point to Bill's comments from the presentation on fish nutrition from PBIV.

"Although vitamins and minerals are required in minute amounts compared with protein, lipid, and so forth, they are critically important, … Every micronutrient has a deficiency disease associated with it, the effects of which are sometimes irreversible or fatal. For a few vitamins and most minerals, excess can be equally detrimental, resulting in toxicity."

Whether it’s in the soil , water or fish food etc or in some product you add, it’s still chemistry in action. They are all part of the whole.