That's called...get some more reef hermits and cerith snails...lol. Look around to see if you have any bubble algae...I'm curious to know. When bubble algae breaks open, it releases spores that grow into hair algae. If bubble algae is present, then get some emerald crabs too.
What are the water parameters? Please list the basic ammonia, nitrite, nitrate and pH, but do also check phosphate levels.
If you are going to run carbon in a reef tank, use reef grade (Kent Marine has) and filter the tank with it for a week once a month. It's not advised to use carbon in a reef 24/7, because it absorbs important trace minerals. A week once a month seems to be effective without robbing the tank of what it needs.
How many hours of light per day is the tank exposed to? Do you have a set of actinics?
The strength of lights and the length of time the system is exposed to light does contribute to algae growth. A typical cycle for a reef is 10 to 12 hours of total light. Having a set of actinics on an independent switch can help cut back on up to four hours of the day cycle by replicating a two hour sunrise and a two hour sunset (on by themselves without the daylights). This only leaves 6 to 8 hours for full daylight rather than 10 to 12, thus less light to contribute to algae growth.
Where is your tank located? Is it near a window? Is there any light that glares on the tank from sunlight (including indirect sunlight)? You may want to try and block off some of the sunlight that beams into the tank.
Scrubbing rocks should be a last resort and best to avoid doing so if possible. This will certainly disrupt the bio filtration. If push comes to shove and the tank is hurting from the algae growth, then take steps to protect the fish and inverts from ammonia spikes....even if it means setting up temporary housing in a spare tank for a couple of weeks until the system re-establishes a cycle.
Also note: water changes also promotes algae growth!! This is because of any phosphates in the water, nitrates in the system and the source of water and also silicates...so don't be too quick with the PWC
. Stick to a simple basic schedule to maintain the water. 10% once a week is sufficient so long as you don't overfeed or overcrowd and nitrates are controlled.