i found a really cheap and simple internal filter had some advantages fo QT/growout. I got them in the $15 range at Wally world. advantages I saw were the way they hung inside as much as anything. Normally that is bad but since looks are not the main concern, I went with the less noise and ease of maintenance. Since the motor and anll parts are in the water, noise is really low due to being muffled and water splash is not a factor. They have an adjustable mount to move it up/down on the tank side. I did not use the ready made cartridge but stripped the original down and then wrapped is in blue/white bonded pad for normal use. For QT and fry where I frequently changed water, the question of bio bacteria was not all that important as the load was so low. Sick fish, newly shipped fish and fry rarely use much food so the load is small. If I had a need for a larger bacteria I would have kept the filter on the back of an existing tank, ready to swing over when needed.
