[pogodzib]

Most fish don't eat hair algae. The only fish that I am aware of that people have a good success rate are an lawnmower blenny, foxface lo, and tangs. The foxface and tangs require a large tank and the lawnmower blenny will only eat very short algae. Even with these fish, your chances of them eating the algae isn't very good. Hand harvesting, keeping your alk high, water quality high, etc... will help the most. Besides for that, there are other options that you could try after that such as adding a phosban reactor, "cooking" your LR, removing your LR and brushing off the algae with a tooth brush, etc...

First though, you should figure out why the algae is showing up in the first place. You say that you added light and sand and the algae could be feed from either source, along with water quality. There is a reason why many/most people say that an RO/DI unit is a must with a reef tank. With the powerful lighting, algae shows up much more often and grows much quicker if the water quality is poor. So, do you use an Ro/DI unit or tap water? Next, just to rule out the light, are the bulbs made for a saltwater tank, and not for freshwater/plants/etc..? (Don't laugh, I have seen it done before so I had to ask.) Third, was the sand that you added previously in an aquarium before? If it has, it may have detritus (waste) built up in it. Also, what size and type of sand is it and did you rinse it before putting it in your tank?