growth in saltwater tank

Question
My friend purchased a saltwater tank already setup for a few years and running with some fish.  Over the last few months he has had to clean the tank of "green" growth appearing on all surfaces in the tank at least once a week.  He's had his water tested several times, but no one could provide an answer or cure to his problem.  Can you?  

Answer

Robert,

Sorry about the delay I have had a bout with the flu.


Generally this  problem has to do with too much light and an exessive nutrient problem. There might be a problem with your nitrate and phosphates.  You can add a  absorptive compound to remove these too excess compounds. This can be bought at your local pet-store.  Where these checked at the store ?  Also there are some fish that are used to control
algae. I love protein skimmers because they naturally remove
phosphates.

Your lights should only be on about 10 hours a day. Any more
and this will feed your algae problem.

Let me know and good luck.
Sorry about the delay.
Todd