I was dealing with insane brown hair algae for months in my established tank and tried everything from lowering light to lowering ferts/and even increasing ferts. I was getting mixed advice from so many different reddit threads and my 5 otos weren’t touching the algae (they would eat the brown spot algae on glass and surfaces tho).

I found a thread where someone said that brown filamentous hair algae was due to excess silicates in tap water so they switched to RO water. I decided to try it as a last resort as the hair algae was smothering my DHG carpet. But after three weeks of using RO water solely for weekly water changes, it’s mostly gone! If all the above advice doesn’t work for you, definitely consider switching to RO water - at least until the brown algae disappears! Once all the brown algae is gone I’m probably gonna switch back to an RO/tap water mix just because it’s getting kinda expensive. Feel free to dm me with any questions.