I still say that a few good sized water changes will take care of things.
For the record, 50ppm is slightly elevated, but not by any means catastrophic.
I have a fundamental dislike for bio pellets, so take my advice (not the water change part) for what it is.
Biopellets, while they DO work, create a different strain of bacteria to combat Nitrates in a captive system. The biggest issue is that that strain if bacteria, and the associated secondary biodiversity that it creates isn't 100% understood. What IS known however, that if Biopellets are done incorrectly, or worse get stopped abruptly, negative things happen more often than not.
I like a system where things run as naturally as possible. Live rock, and undisturbed areas of a sandbed contain anerobic bacteria that naturally consume and lower Nitrate.
In our captive system's, especially smaller systems like yours, things potentially become out if whack sooner than in a much larger system. All of this leads to my probably much to long reply.
Bottom line. Biopellets DO work, but with potential negative concequence.
Water changes are simple, cheap, and just as effective without the potential negative effects of another reefing gadget..
Just my 2¢. Please make your own decisions. Just know the facts.
I wish you all the luck in the world.