My good friend has a 15 gallon tropical community tank at her house and it has done well for a few years but all of a sudden her family is having to clean out the algae almost every single day! Even to the point of removing all the fish and decor and scrubbing it down and two days later the water is green! They have three corys and a few shrimp in there but I guess they can't keep it down. Nothing has changed that she can think of and we are both stumped. Any ideas as to why the algae would just appear??? It is a heated, filtered tank that has been running successfully for a few years. No recent change in location or anything else that we know of. She doesn't live at home because she is in college so she just gets word from her parents. Does anyone have any suggestions on how to control the algae?