Nelson City Council staff say that a $135k trial of Diatomix in the Tahunanui Modellers Pond is a “good spend of money”. Photo: File.

Council defends Modellers Pond trial


Nelson City Council staff say they are confident that a $135k ‘biological product’ trial will cure the ongoing weed woes of the Tahunanui Modellers Pond.

The trial, which is expected to last between three and 18 months, was scheduled to start on Monday and involves the use of a nano-silica mixture called Diatomix that generates oxygen and cleans the water.

The trial is being implemented with the support of the modellers pond project group, including representatives from council, the Modellers Society and the Tahunanui Business Association.

At Thursday’s works and infrastructure meeting, chair and project group member Stuart Walker told councillors that they are “really confident” it will work, with the approach being effective in similar situations in Australia.

“It’s nanotechnology … essentially it’s starving the food source of the algae,” he said.

But some questioned the cost of the trial, having last been told the budget for the pond was $65k.

“We haven’t had anything come back to us to increase that budget, so I’m just a bit confused,” said Gaile Noonan. “This is almost twice as much.”

But Alec Louverdis, group manager infrastructure, confirmed that council does have a budget in the current financial year to cover the cost.

“We have faith in the trial and this is a good spend of money,” he said.

Stuart said the original cost was expected to be much higher before being adjusted – with the initial cost being just over $200k.

“We’ve started into it and learned some of the items that were reduced from the 200 figure down to 65k have had to be reinstated, which we weren’t aware of.”

Council CEO Pat Dougherty also defended the cost.

“This is an exciting option for us and substantially cheaper than any others, so we are running with the trial.”