What is brown algae cause from in a fish tank?

Answer 1

Too much nutrients in the water is the primary cause of all algae, including brown algae. Generous and frequent water changes will take care of the majority of the problem. Be sure you are changing at least 25% of the water in the tank once a week. Use a gravel siphon and clean the gravel as you go and you will see the vast majority of your algae problem disappear within a few weeks.

MM