Rather than add more filters which do add more time and work to keep cleared, I add small powerheads. If the powerhead is too strong, I add baffles to cut the flow to closer to what I see needed. I use several of the little heads I get from the auction site for about ten dollars as they have a nice suction mount that I like. The specific one I use is from a dealer in Madison, Wisconsin as he seems to have a good service and price.
However, I have also used small fountain pumps, simply due to having them on hand and they are also able to do the job if I set them up off the bottom to avoid fouling from too much debris. They come in such a wide range of size and performance, there is one which would be right for what you see, but it is likely to take some guesswork to get it correct.
One handy way to cut flow is adding a net over the intake or the outflow.
I object to equipment in the tanks, so I have drilled/cut out the center of wood and placed pumps inside, letting the flow come out the top to spread out horizontally from there. Kind of a pain to cut and fit but it does get a gentle flow all around without blowing things too much.
Point to keep in mind that may bother some? There is often worry about "straining" motors but that is not a factor in the magnetic drive pumps/filters we now use so we can choke them down as much as we want without burning them out with the note that we do need to keep them wet. We do need to keep them wet but we can let them totally stop without harm as evidenced by the number of filters which stop until we get them restarted and it doesn't harm them.