Yup Jay,as a fellow reefer that started out mixing 5 gallons at time innna bucket in the bathtub,,,,,thefatman said:this i did not know..
i mix my saltwater exactly 3.2 seconds before adding it to the tank
i pour salt and water into bucket, and stir, then dump in sump.
guess i better change my plan.
(see i can learn something)
that was 15-20 yrs ago,,,now it's 55g rubbermaids w/ PH 's and heater,,,,
IMO made up SW has a longer shelf life than just RO /DI sitting the bucket.
as my water is filling, i throw some salt in there just so it's not "Freshwater"
RO/DI CAN go "stale" i'm told,,,,
like Tom said,,,ya gotta let the mix,,,,mix.