Any floating plant will do as well. It'll intercept the light before the algae can get it. I find that my big cichlids like things floating in the tanks to hide under, so bonus there. I have a young pike cichlid I'm growing out that was very skittish until I put some foxtail in the tank... happy as a clam now.
You might also try growing something hydroponically on top of your tank to soak up nitrate.
Or make a nitrate filter... there's a couple threads going about those right now. Not a big enough problem for me to invest that effort, but to each their own.
