When our in ground pool was installed they didn't haul off the soil they dug up, they spread it all around and sloped it gently away from the pool.  We didn't get around to doing any landscaping for a while and some soil blew in the pool and has caused stains.  The soil they dug up that blew into the pool is what I call "Georgia clay".  It's used as foundation base under concrete slabs here in the south.  I think it must have iron in it.  Someone said to use muriatic acid poured into a 2" pipe with a brush attached to the end of the pipe.  Would this work?  Would the muriatic acid flow to the bottom of the pipe and force the water in the pipe out?