[2] In July 2007, Nottingham Forest signed Hartmann on a free transfer joining as a third year academy member.

By July 2008 he was released and signed for Bognor Regis Town on a free transfer and made five appearances for the club.

[citation needed] In early September 2011, Hartmann signed for Filipino side Loyola Agila, thus joining his two brothers who already play for the club.

[5] Hartmann received his first senior call-up in November 2006 for the 2007 ASEAN Football Championship qualification tournament in Bacolod.

[8][9] In the Long Teng Cup, he made his first senior appearance since his debut in November 2006, playing the full 90 minutes in the 3–3 draw against Hong Kong in the opening match.