I don't have any pre-teens in the house anymore.  My son was a competitive swimmer, so his shampoo needs were a bit unique.  We found Aussie Mega to work well at removing the chlorine and keeping his hair clean.  It is a good clarifying shampoo.  I do recommend using a good conditioner with this shampoo, he used the Aussie 3 Minute Miracle regularly with good luck, however, I found it to be too much for using all the time.