(Radio Iowa) – The aquarium at Dubuque’s National Mississippi River Museum is closed due to a chemical leak. A pipe from the museum’s H-VAC system dripped glycol into one the aquarium’s 40-thousand-gallon tanks last week, killing all but 17 of the fish inside on Tuesday. Aquarium staff were alerted to the presence of glycol in the water due to a milky bacteria blooming in the water. Kurt Strand, the museum’s president and C-E-O, says that made rescuing the fish difficult. “Bacterial bloom can happen in a few short hours,” he says. “As soon as our team got in at 7 a.m., it was all hands on deck. They knew they couldn’t dive in because it was murky, but they were doing everything possible to save as many as they could.”

The H-VAC leak was first identified in early October and was patched. Strand says museum staff had been watching the tank’s oxygen levels and had introduced bacteria designed to detect and fight chemicals in the water. “When they took the steps they took and the figures that were coming for the oxygen in the tank and everything else, I felt like we were past that time where something could happen,” Strand says.

Strand hopes to reopen the exhibit in about six weeks, but that depends on the health of the surviving fish.