pre-mixed water

[Kabong]

It will be fine.
If you want it for emergency you can keep a power head and heater in it.
If not just put them in 24hrs before you want to use it to get the O2 level back up.

[Ruth]

Totally agree that it will be fine - just make sure to cover your bucket to make sure that no bugs, dust etc. gets in. Also check all params before using to make sure that they are OK and you haven't had any evaporation etc. that can change you salinity.

[MikeP]

Thanks for the help. I figured it would be fine. Bucket is covered and I had a spare air pump so I ran a hose and small airstone in there for now.