Algea Buildup on Back of Tank

My 75gal reef tank is starting to look bad on the back wall, should I clean it once in awhile or leave it? When I clean the water and stir some of the top sand the back usuall looks real bad especially with that sand stuck on it. :huh:









1 - Yellow Tang
1 - Coral Beauty Angel
1 - Yellowtail Damsel
3 - Common Clownfish
2 - Peppermint Shrimp
100# + - Live Rock
160# - Live Sand

I don't like the look but it's probably beneficial to my water. The only thing my fish don't eat it on it much they do some but not much.