Harbour was too strong up front for Alhambra-Union, winning 45-22 at Watson Park.
The visitors showed some spirit, nabbing two late tries to secure a four-try bonus point.
University A beat Dunedin 23-17 in a tight encounter at Logan Park. Dunedin lock Harry Dodds was badly injured during the fixture and was taken to Dunedin Hospital.
Taieri kept its unbeaten record alive with a 25-15 win against Southern at Peter Johnstone Park.
Zingari-Richmond had too much class in the midfield, beating Pirates 43-29 at Montecillo, while Kaikorai dispatched Green Island 47-17 at Bishopscourt.
Video by Otago Polytechnic