Hair algae only on half the tank?

[LizardLou]

I have a 37g tank with two rock structures on either side. Hair algae seems to be growing really well on one side. I'm doing my best to pull it/toothbrush it off when I'm doing water changes 1x weekly, but it comes back in full force. My lights are centered over the tank (ai hydra) and I have a powerhead on each side of the tank just a little staggered. Not sure why this is happening. And it's been like this the last two months (6 month old tank). I use strictly RO/DI water. Have a skimmer and a filter. Pretty purple coralline algae is starting to grow on that side, though.

I tried getting (renting) a sea hare from my LFS, but the guy tried to hand me a softball sized one.

[brandon429]

One option to explain one man's take on the matter, and get a handle far better than tooth brushing, would be to post detailed pics of your tank in this thread, do a search for it

Pico reef pest algae challenge thread. We fix green algae probs there, all the info is there in sixty pages of before and after pics.