I do not most of the time, the only exception was in the salt water in the winter. I don’t think most people do unless the water stays cold or you are doing a large water change, but others may chime in on what they do.
I do keep a pump running in the salt water container. I use a maxi jet with a hose attached to the outlet in both containers to transfer water. So I use to mix the salt water also and just leave it running.
