sounds like he has cyano bacteria, its not a true algae although considered just as annoying.
1)is to asses how much water movement he has, size tank etc...... if he has a 100 gallon tank and hes only turning 200pgh, then that is probably not helping his case. low water movement allows sediment to settle in certain areas, which will aid the cyano in nutrients.
2) water changes. Removing the nutrients in which the bacteria uses to grow, will help slow down and eventually rid the algae from the tank. Along with water changes, using additional powerheads as needed and manual removal, will help rid bacteria of the tank as well.
3) increase either frequency or amount of water change(s). If hes not doing water changes often enough, then his nitrate and phosphate levels have large opportunities to exceed levels 50ppm nitrate, and 10-20ppm phosphate, which are some of the most common causes to algae problems.
4) it has been suggested that old light bulbs could also be a culprit too algae/cyano issues. May be worth figuring out how old the bulbs are, and depending on the fixture and average age of bulbs, then maybe replace them as well.
