"We are just not good at this sort of stuff, we have to be very careful with what we do with other people's money," Cr Mallett said.
"We walked in here with our ratepayers facing a huge increase and we are going to walk out of here with our ratepayers facing a huge rates increase."
Councillor Angela O'Leary responded to councillor Mallett's comments.
"We are local government and it is very simple, we are here to provide the services that the public won't or does not provide," Cr O'Leary said.
"Sometimes Councillor Mallett, those services we provide include libraries, zoo, parks and playgrounds."
She called it hypocritical of him to make those comments when he supported putting aside $7m to purchase and hold buildings on Victoria St.
Councillor Dave Macpherson said rates had been cut without slashing projects the people want: "I wasn't a zoo expansion upgrade supporter in the past, but Councillor Ryan has done a lot to convince me in the last couple of days.
"This will be a better zoo development than anywhere I've seen in New Zealand and Australia."
Mayor Andrew King and councillors Leo Tooman and Mallett were against the motion.
Deputy Mayor Martin Gallagher and councillors, O'Leary, Macpherson, Geoff Taylor, James Casson, Mark Bunting, Paula Southgate, Rob Pascoe, Hamilton and Henry were in support.