Ok, in my case, the hair algae, or at least I think it's hair algae, looks much worse than the pictures here. They are long, blackish color, but really very dark green, and grow like crazy--within a week, my Amazon sword looks like it's wearing a wig.
I don't use CO2, but do dose liquid fertilizer at every water change, but only enough for the new water, as I don't want to overdo it. I also placed fertilizer tabs in the sand when I planted it--been a couple months.
The light is on from the time I leave for work in the morning until after supper (approx 11 hours) and I have a double bright LED, which came with the tank since it's 20" deep. So, I'm guessing I'm using too much light and need to get a timer to shut it off mid-day for a couple hours. But do I need to up the fertilizer? How do I know if I'm using too much?