User blog comment:Baneares/Countdown to Earthlings/@comment-4958495-20120504155207/@comment-4454131-20120506010222

Garth was off limits early in the development of the show so they made a new Aqualad, Kaldur. When Garth became available, they already put in too much work for it to be worth switching back (that and as the creators of Kaldur, they like him) so Garth only showed up when we got to see atlantis.