I've been using a freezer for years with circulating pump with media and charcoal filters.
I run several air aereators pumps and have a timer to run freezer a hour and off an hour keeps temp around 55 degrees except in winter months l will regulate as needed.
Change out about 50% of water everyday or every other day.
I currently have downsized my tank to a 5 cu ft freezer which will hold 2 13x13x21 wally world laundry baskets.
I but shiners by the pound and this keeps a pound of minnows small or mediums well.
Every morning as l am loading minnows in 5 gallon bucket l fill bucket with cold water from freezer as to not change water temps.
Then l add lake water back to freezer tank.
I use a double 12 volt aerator l wired in boat to run air tubes to bucket.
I carry around a dozen or more frozen soda bottles in ice chest to add to bucket all day long to keep water cool.
Colder water holds more oxygen but you have keep wayer oxygenated.


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