I have a couple to rubbermaids plumbed together with a pump and hooked up to my RO/DI. Dump salt in and let it mix for awhile.
Hook the hose up to this fitting to pump water out of the tank:
Then I reverse the hose and hook it to the plumbing on the water change station to pump water back to the tank.
A bit on the slow side but it works our well and I don't have to carry water.