Bad case of hair algae...

[IworkatPSP]

My friend has a bad case of hair algae in his 20 gallon, is there any way to reduce/get rid of it?

 

[RMPD109]

Check the tank for phosphates. It is normally the cause for nuisance algaes. Then try to determine the cause for the excess phosphates and stop it. Once this cause is stopped so will the algae. Possible causes are overfeeding, food type and overstocking.

There are plenty of bandaid options such as phosphate reducers and reduced lighting but nothing will cure the tank but stopping the excess nutrients.