What grit to use for tongue depressor hook sharpener

Ive read the threads about sharpeners. I like the idea of a homemade, floating sharpener. So, what have you all used for the sand paper in the past to make one of these up?

They really seem inexpensive on amazon, http://www.amazon.com/s/?ie=UTF8&keywords=fish+hook+sharpener&tag=mh0b-20&index=aps&hvadid=3527179063&ref=pd_sl_7kiovvkgf7_bb

I would think a typical nail file would be just as good.

I bought a sander belt and tore it into strips. It works great for salt sharpener. No rust. I think I used 80 grit.