Not to hijack the thread, but I'm having the exact same problem which started around January. I attach a picture from December, and a current picture (which is not out of focus... there is hair algae everywhere and makes things look fuzzy).
- 10G JBJ Nano cube, standard 100gph pump, no filter media other than floss, cleaned twice a week
- Water params: 3 dkH, 6.7 pH, temp 22-24 C
- Lighting: 2x 24w 6700k compact flourescent, 8hrs per day
- Dosing: Seachem micro, trace, nitrogen and phosphorus, 0.5ml each, twice a week
- Pressurized CO2, comes on with the lights
- Water changes 50% once a week
- Plants: hemianthus calitrichodes, lilaeopsis mauritana, echindorus parviflorus (the algae coats this plant and is suffering), rotala wallichii (choked out), hygrophila augustofolia, dwarf hairgrass
- Critters: 3x amano shrimp, bladder snails, 9x dwarf rasboras, fed ~4 flakes every other day (they are super tiny)
In December I had an outbreak of green water which was solved by a UV filter, and it has not come back. I then noticed one strand of hair algae but didn't think anything of it. I went away for work for about 2 weeks, and when I came back the whole tank was taken over by hair algae.
I've tried withholding ferts and a 3 day black out. Stalled the algae, but didn't kill it. I've been removing it manually since then, and its quite tenacious, and clings to everything. Its impossible to remove it all from a surface (other than glass) as it clings quite solidly. I then tried boosting CO2 and reducing lighting by 50% for about two weeks, and also not adding ferts. The algae slowed, but failed to die back. My latest strategy is to resume light intensity and ferts, as I've seen some patches where the algae seems not to want to grow, so I'm thinking there may be signs the plants can fight back. Also, it seems not to want to grow into the underlayer beneath the lilaeposis canopy (grass-like plant); maybe light intensity related.
Would be interested to know if the surface plants or addition of other fast growers worked out for you.