How Long Does a Fresh batch of Saltwater last?

[justinl]

premixed is fine, aeration is... probably okay? but do not keep it heated. Heat = bacterial growth and death which will make your water not so fresh. I keep my water sealed (with duct tape) in 5g bottles, cold and without aeration for up to three weeks. If you can keep it in the dark, like in opaque rubbermaids, that would be even better. Follow that and i think you could probably store it for a couple months.