one thing i can say, is if youre talkin about "mixed nutes" id agree with zandor... just divide your gallon formula by 4 and use quarts to feed instead of mixing gallons....... but if you have to... just keep your mixed nutes out of the light...

store only in te dark, once i mixed some nutes in a 20oz. bottle and left it in the room under the lights and it started to grow a floating mold in it.....

yuck