I have been using standard garbage cans for years. When I get a new one I wash it out with bleach diluted in water then rinse and scub with just water.
I mix salt in the water 2-3 days before needing it for the water change and keep the pump running the 2-3 days to get it all mixed very good. The day before the change I turn on the heater in the trash can to get the water up to Temp. (I keep an extra heater on hand for an emergency spare and just use the spare for the pre-heat of the water.) ALWAYS re-test the salinity before you siphon water out for a change! I had been inturrupted once while mixing the water for a change and forgot I did not finish adding salt. I almost dumped it in my tank but something made me re-test and I caught it.
Good Luck,
WW