Phosphate Sponge Pros & Cons

I've been having trouble with green algae growth on my sand bed the last
couple months. I feed very little, my lights are only on about 10 hours a
day and my skimmer is working great. My crabs and sand sifting star do a
pretty good job of keeping things mixed up but I have to manually stir
things up every 3-4 days to keep it from progressing. The algae is not
affecting my corals, rocks, glass just the sand bed. Today at my LFS I
mentioned my problem and they suggested a Phosphate Sponge. I'd like to
hear anyone's pros / cons on the use of this.

Thanks,
Brad