Review my fert solution mix

[_Maq_]

to use demineralised water (sold at car shops, paint shops, etc) to prepare the fert mix instead of distilled water

I believe that most of so called distilled water is in fact RO water, because treating water with RO is cheaper than distilling it.

do I need to add excel to the fert mix or just adding vinegar and E202 should be enough ?

You don't need to add anything as long as no chelates are included. If you do use chelates, you should not blend them with macros. For conserving chelates, I think cold & dark = fridge is the most sensitive way.