There's never a need to refrigerate macros, sometimes it can help micros/Fe as far as mold goes (I believe that's the only reason).
It's good to add a little vinegar to the micros, something like 5 ml per 500ml solution. It helps prevent mold, and more importantly drops the alkalinity, which will help keep the various elements in an available state.
Excel/Metricide will also prevent mold but it doesnt help the PH.
Short answer: No
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