I have hair algae in my 55 gal planted tank. It's been up for 5 years,
filled with crypts, swords, anubias, hygros, water sprite, and many
others. I use 4 55 watt PC's 6400 K on for 12 hr.., CO2, 50 % monthly
water changes, and weekly Fe/K supplements. I have 4 SAE and 6 Amano
shrimps (anyone know of an online source for Amano's?). Fish are
Rainbowfish. My other tank uses the exact same everything except for
having tetras, and has NO algae......Any and all suggestions are
appreciated.

Dave

I don't know all of your parameters, but I had a recent outbreak as
well. I tested and found my Fe levels were good to high, and my Nitrates
were very low 4ppm.

I had luck by adding just nitrates and holding off on the iron
supplements. I've noticed Hair algae can be a bit light sensitive as well.
I have two metal halide lamps, one of which fails to fire on occasion. When
this happens the hair algae usually dies off, even if I light the lamp a
couple hours later.

So, as a first step, test your Nitrates to be sure they are high enough,
with your lighting levels the plants will be consuming Nitrates rapidly. If
they are low, bring that up and see if your situation improves.

If that doesn't do it you can try cutting back on iron. I've seen no
conclusive study on whether or not this is effective, but it seems to work
for me.

As a last step alter your lighting schedule (start 2-4 hrs later one day,
end 2-4 hrs early on another). The fish may not enjoy this much, but I
don't believe it will stress them that badly. Or you could use the full
hammer and do a black out.

Playing with lighting, especially a full black out, will probably work but
won't address the real problem. I suspect it's a combination of light
levels and fertilization balance. (Since you have so much light, you'll need
a lot of fertilizer so the plants aren't limited).

Hope something in all of that proves helpful!

Rod