He came back later on Wednesday evening to win the 800m freestyle in 7:58.30, nearly five seconds inside the previous New Zealand record set by Dylan Dunlop-Barrett. Capp became the first New Zealander to swim under eight minutes.
Earlier on Monday night Capp broke his own Bay of Plenty record by two seconds in finishing fourth in the 400m freestyle final.
And he still has his favourite 1500m freestyle race to come tonight.
Capp made headlines last year when he swam an astonishing race at the New Zealand Short Course Championships in Wellington to take a remarkable 16 seconds off double Olympic gold medallist Danyon Loader's 1500m freestyle time. Loader's record had stood for 22 years.
The last competitive race Capp had before this week's nationals was the 2.6km Sand to Surf ocean race held at Mount Maunganui last month.
Capp said after he beat Rotorua's ocean swim specialist Kane Radford to the finish line he was building his stamina up for this week's nationals.
Judging by his performances this week Capp is peaking at the right time.
The world championships in August will be the ideal forum for Capp to show those New Zealand Commonwealth selectors what they missed out on.