The macro algae Chaetomorpha has become a reefers best friend in the last few years, beating out Caulerpa as the macro algae of choice. Chaetomorpha is generally placed in a refugium that is connected to a saltwater reef tank where it is usually balled up. This macro algae has many benefits to a reefkeeper but generally its sole purpose is to absorb nutrients such as nitrates.
Chaeto as it is sometimes called has the ability to host a whole mass of saltwater organisms such as pods, mini stars, and worms. When properly cared for it grows into a dense ball that gives the organisms a place to hide. Chaetomorpha is preferred by reef tanks owners over Caulerpa becouse unlike Caulerpa it does not go sexual. When Caulerpa goes sexual it releases most of its nutrients it has absorbed and it could cause a tank crash. Using Chaetomorpha will help fight nuisance algae by feeding on nutrients that are used by nuisance algae thereby creating a healthly competition between the algaes. 
Chaetomorpha is best used in a refugium with a little flow and a light. A lot of reefkeepers have had success growing this macro algae with a basic compact fluorescent 75 watt (5100K) floodlight, although for best results its better to provide a stronger light (6500k @ 45w CFL Bulb).
Chaeto is a type of beneficial algae grown in aquarium sumps to remove excess nutrients and pollution. It appears to be the hardiest type of good algae. We are always amazed how it will survive a variety of conditions and light levels.
Using Chaeto in Mud Filters
Chaeto is a one the best types of macro allergies as far as using it to filter your system. It resembles a green Brillo pad and is phenomenally hardy.
It will also serve as a house for all sorts of critters such as copepods and feather dusters. Often if you buy it from a farm, it will already have many of these inhabitants in there. All of these together will help to balance your system in a positive way.
So we highly recommend buying a bed of Chaeto and using it in your sump or mud filter.

You should get tremendous growth in the Chaeto and not in the hair algae !