As long as your tank has power heads in it to move the water around, it will be fine untill tomorrow (provided the salinity isnt too high.) Just turn the pump off untill you can get to the LFS
today. Its not uncommon at all for my sump to evaporate enough off in one day that the power head will create a whirl pool and suck in air. I just throw the switch, leave the power heads running, and refill it the next morning.
You can run a tank w/ LR
, power heads, and a skimmer. Its called a Berlin system. I ran one for years w/ no problems.