Can you answer the questions? Am I to take that as a yes, you are pre-mixing your nutes? Don't do that unless they were designed for it. A hydro nute is meant to be stable over time, diluted, in a res, at pH 6 or so. Even if you use a hydro nute, adjusting the pH into a different range may make it less stable.

Use your nutes immediately after mixing. Don't let them sit.