My tank is 3 months old. So far, it has been good. I do EI dose every other week. And I do only half dose. Light is on for about 7 hrs with CO2 about 1 bubble per sec. I do water change every other week.
Only recently this showed up. Is it green hair alage?
What kind of light how far off the substrate over how large a tank?
How much EI type nutrients dosed each week?
I zapped it with Seachem Excel and moved the powerhead so more water movement over that area and haven't seen it since. To zap, turn off the filter and powerhead so water is still, squirt with a dosing syringe or pipette the daily dose on problem areas and let the tank sit for 15-20 minutes before turning the filter back on. It turned pink and the otos and platies ate the 'cooked' algae for me. If the plants that are infested are not doing well then trim off the bad leaves though. Algae are more likely to infest weak leaves and they might as well be pruned off a bit early.