Artist Jonny 4Higher, now 37, said the crew all started as graffiti artists, but most now had professional art careers in New Zealand, Australia and Germany.
Bobby Hung, 30, now teaches art at Unitec and has worked as an artist in Australia, Asia, America and Europe.
"I had a goal to paint in 30 cities before I was 30. I have achieved that," he said.
Their art on the tank looks indecipherable at first glance, but spells out words that mean something to the students such as "dance" and "empathy".
"Dance is a way of expressing myself, like graffiti," said Lennox Kaitapere, 15.
"It makes me feel cared for," said Josh, who doesn't know where his dad is and lives with an aunt.
Phoenix Peachman, 15, said he tagged "just to get known, to get your name up there".
Lennox said some mates "got kicked out from school. That's not the track I want to go down. I want to at least finish Year 12 and get qualifications to get better jobs."