"I had a little idea I was going to break the record but not by that much. It was a big surprise. I did go out really hard and tried to hold on as long as possible. It was another solo effort, just trying to lap people as much as I could. I am really, really happy with the time I went and it has pushed my ranking up a lot."
His 1500m time ranks him 13th in the world this year, just ahead of Canada's Ryan Cochrane, who recently won the Commonwealth Games gold medal.
Capp, who broke the national short course 800m freestyle record in August, says it topped off an awesome week for him.
"I had a little bit of disappointment at the start of the year not making the Commonwealth Games, and then been training all year for this really. I've done all I could have hoped for. I'm stoked."
Capp also won gold in the 400m medley and silver in the 200m medley in Wellington. All but one swim was a Bay of Plenty record, including erasing his cousin Moss Burmester from the 200m freestyle record books.
Capp was equally delighted with the performances of some of his young Greerton club mates. His younger sister Claudia, 16, won gold in the 200m butterfly, and Libby Bradley, 15, won gold in the 50m freestyle.
"Greerton Swimming Club has been really good to me so far over my swimming career," Capp said. "They always support me and I love still racing for them, who I have been racing for my whole life."