Right now I actually only have it running on a cheap programable timer. I just got my Apex back up and running within the last week or two and haven't had the time to deal with it.
And yes, 45 min is what it's running. That's a wee bit more than 3 gal, but close enough
In the new SW barrel there is no equipment. No heater, no power head, nothing. If I think of it, I turn on my mixing pump once a week to make sure nothing settles, but I haven't noticed anything after I have made and mixed the batch well. My original plan was to put the mixing pump on my Apex and have it come on once a day for a few minutes, but I still haven't done it yet.
I'm pumping the 3 gal water change it into roughly 300 gal of tank water so I'm thinking any low O2 or temp difference won't hurt anything.