My 55 gal. ran for a good year or so (I flipped my old one and added a sump) with 40 ppm. My LFS buddy suggested Halimeda. Since you have a fuge you could put it in there, I put it in the display, on one side. I didn't mind Green plants in the display plus it is non-intrusive. Nitrates went to 0 after about 2 weeks and never had detectable levels ever since. If you find some and want to add to fuge, don't bury the root ball, just let it rest on top of the substrate and cover just a little, it will grow down itself.