Very seldom will any vehicle get algae in the tanks, have the shop prove you have algae. Algae requires water and sun to grow, 99% of the time algae will be pumped in, and that can't happen with filters in line. Your first symptom will be continued clogged filters. and low fuel pressure shut downs.
Black fuel is not algae. take a sample and have it analyzed prior to paying big bucks chasing a problem that you don't have. BTDT over the past 4 years.
Algae develops a slime that will not pass filters. If you do not have filter problems, 999 times out of a 1000 you don't have algae problems.