Recently I've seen and felt several (50-60) bumps in the bottom and sides of our fiberglass pool. The bumps range in size from 1" - 3" and are convex shaped. They are really only visibly noticeable in the shaded areas and protrude no more than 1/4" - 1/2" from the sides or bottom. The pool is 12 years old and has never been drained or even lowered below the skimmer. The water chemistry is all in line with ANSI/APSP guidelines.

We've recently had a large amount of rain (Appx 3" - 4") in a very short period of time and am curious if this could be a factor.

Has anyone else here had this occur? Is there anything we can do to get rid of them? And could this be a sign of a greater underlying problem?

Thanks in advance, any comments would be greatly appreciated.