The rocks have coralline algae which is a good thing. The sand looks like cyanobacteria (I may be wrong) which is not. It is also called red slime algae and usually grows in sheets starting as patches. Yours looks more dust like so it may just be diatoms (normally brown).
How many gallons is the tank?
How long has it been up and running (since being cycled)?
What type of filtrations are you using (Live Rock, canister or HOB filter, etc.)?
Describe the lighting units (type bulbs, total wattage, and age of the bulbs)
What are the current water parameters? Ammonia, nitrite, nitrate, pH, salinity, temp, calcium and alkalinity. Please post numbers of results.
What are the current tank inhabitants?