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I have this algae (I think) on the walls of my tank that's hard to get
rid of. It takes some serious scrubbing, but comes back. It takes the
form of streaks (see link for photo).

http://www.aquariumadvice.com/download.php?id=4599

I've posted this elsewhere and it was suggested that otos in my tank may
have scratched the acrylic, leaving a surface for diatoms to get in.
Either that or it's bba?

Any ideas? Suggestions?

Params:
12G acrylic
~1 WPG
temp ~70-74F
ph: 7.8
gh: 10 deg
kh: 5 deg
ammonia: 0
nitrites: 0
nitrAtes: they should be approx 10ppm by now (usu gets to around 10 when
water change due, as it is today.)

I've been slackerly and changed the water biweekly, 2-3 gallons.