Hornwort and water sprite works well.
But it grows really fast and needs to be submerged.
Pothos, only the roots are in the water.
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I have put cryptocoryne to use in sumps as a submerged, low light, low growing plant. The entire sump, using a shallow bed of sand became a massive tangle of roots and nitrates held between 2-5ppm, although they are no substitute for, and I continue with lots of regular water changes.
below is the sump, during a water change, you can see the pump chamber walls used to keeps roots from growing into the equipment
I also use separate refugiums in between some tanks and sumps (solely used just for gear like pumps, heaters and filter socks) to house emergent and floating plants where possible (some with pothos).