help please! algae over growth

[torrid_07]

yes i have a sand sifting star, crab, shrimp and some snails. and they dont seem to do too much. should i mix up the sand? get particles to flow through the filter?
ive thought of getting a couple of shrimp gobys mabye?
but yes my ph ca nitrates and nitrites are all good.
my specific gravity is a little on the high side.
would that do it?
and other than the inverts i only have 4 fish so its not like i have a huge load.
im not sure really what to do now.