I'm assuming that you have a concrete pool?
(Hopefully, nobody would tell you to use a wire brush on any other type of pool! If they did, they are truly a pool idiot!)
If you have a vinyl or FG pool, it has to be scale; there's just about no other way for the surface to get rough like you've described. Removing the scale from those pool is pretty easy.
If you have a concrete pool, however, it's harder. The problem is the scale is usually calcium carbonate . . . and so is at least some of your pool's surface.
But if it's a plaster pool (Marcite, marble aggregate + white cement), then the other possibility is that it's the opposite of scale; the roughness is the result of low pH for an extended period (or very low pH for a short period) causing the surface to erode.
You can get a pretty good indicator of which it is by examining non-concrete / plaster submerged surfaces. Scale will usually form on metal and tile surfaces as well as on the pool surface. Erosion will be confined to the pool surface. Also scale will be above the original surface; corrosion will penetrate below the original surface.
Post what you find. It will help me if you fill out the pool equipment form, too: http://pool9.net/pf-equip-form
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