We used to use a drag harrrow, and had really good luck with it. The problem we had was our arenas are so large, that after time, you would start to see them getting wavy. If you arena is pure sand, you should be alright. We went to a parma arena groomer and that helped a bunch. We pull the groomer with a ford 8n and it seems to work well. The only downside is that it was 1500 dollars. But I think a drag harrow on sand would work well, and if you have a blade to level your arena, that would work too.