Do aquatic plants reduce nitrates?

I ask because I thought they do but my planted Biocube 14 constantly has high levels of nitrates (25-100). I'd say my BC is moderately planted with crypt windtii, dwarf sag, rotala indica, some water wisteria, an anubia frazeri, and some hygrophilia augustifolia. I have 4 neon tetras, 4 red cherry barbs, and 2 otos.

My ammonia and nitrite levels stay at 0, the GH is usually around 2 and the KH is usually around 12. I was using Excel and Flourish twice a week but have backed down to once a week. Temperature is around 75-76. I also do a 50% water change every week and try to stir up as much detritus as I can.

Part of the problem was I was over feeding and have cut back on that. I think the other problem was I was only changing out the filter floss once a week. I'm starting to change it out twice a week now. I'm also thinking of adding a twig from a pothos plant in the sump portion of the BC 14 to help reduce the nitrates. I've read on several sites that potted plants like pothos can remove nitrates directly where aquatic plants have to convert it back to nitrites or ammonia first in order to use it. I don't know if that is true or not and I cant find any studies or reports that support that.

Thanks.