Family's 'scary' near miss as pool device 'explodes like a bomb'

Chemicals are 'very reactive' and should never be mixed with other substances – but warmer temperatures are likely to blame, an expert chemist warns.

Aussie pool owners are being warned about the danger of "chlorine bombs" after a pool-cleaning device exploded, narrowing missing a child who was swimming at the time.

A parent and their daughter were swimming on a hot day in Melbourne over the weekend, with temperatures reaching 38 degrees in some areas, when they noticed the floating dispenser holding chlorine tablets "smelled like rotten eggs".

"I told her not to touch it, and I grabbed the stick to push it into the corner," the parent wrote on social media. "And it exploded like a bomb. Literally a bomb. The device shattered into pieces, there was a loud bang, gas cloud and my ears are still ringing."

Pieces of pool floater after it exploded.
The floater, which releases chlorine into the pool, exploded while a child and a parent were swimming. Source: Reddit

Warning over pool product sold at Bunnings

The device in question is designed to float on top of the water as the chlorine tablets inside slowly disintegrate. It's an alternative to using a liquid-based chemical. The poster said they used Hy-Clor 3-in-1 tablets sold at Bunnings. However, Hy-Clor told Yahoo News its 3-in-1 range does not come in tablet form, only in a granular chlorine concentrate, and cannot be used in a floater device.

The exact floating device the poster used is unclear, but it appears to be the Hy-Clor Pool Floating Dispenser, also sold at Bunnings. Hy-Clor declined to comment on the pool user's experience.

After the Melbourne pool user's floater device exploded, they warned others against using them, especially during hot weather.

"Apparently above 30 degrees, the pressure builds in those floaters [from the] heat/sun and chemicals and [it] caused a chlorine bomb," the poster suggested. "If we had been any closer we would have been seriously injured. Warning to parents pool floaters are dangerous".

Hot weather likely to blame for chemical reaction

Ian Rae, a chemist at the University of Melbourne, confirmed chemicals are "very reactive" and should never be mixed with other chemicals. In this instance, he suggested the chlorine likely reacted with the hot plastic.

"Chemicals are known to be sensitive. The manufacturers know that, and they take a lot of care to package them so that they're as safe as they can be — but every now and then something goes wrong," he told Yahoo News Australia.

"They're clear signs these things are dangerous and you've got to handle them carefully. And most of the time, I think people do handle them carefully and nothing goes wrong."

Left: Hy Clor 3 in 1 pool chlorine. Right: Hy Clor floating pool dispenser.
The poster said they use Hy-Clor products sold at Bunnings. Source: Bunnings

He said it's likely not to have been human error in this instance, or a fault with the device necessarily. But the floating device "must have got very hot" in the sun and reacted with the chemical.

"Hot enough for the chemical inside to start decomposing," he said. "The manufacturers say [they] can't decompose, but it's just extreme conditions when the pool chemical probably reacted with the hot plastic".

High temperatures can cause release of 'toxic' gas

The product's safety data sheet stipulates "exposure to high temperatures or contact with acids may liberate chlorine gas which is toxic". It says the product should be kept in a cool place, preferably below 30 degrees Celsius.

"Thermal decomposition may result in the release of toxic and/or irritating fumes including chlorine gas and nitrogen trichloride," it says. Exposure to this chemical can cause throat irritation, Rae said.

But chemicals in general are "rather unstable" the professor warned, and can react "quite quickly with other substances". That's why they'll always come with warnings such as "keep them cool and don't mix with other things".

Someone claiming to have worked in the pool industry "for years" responded to the warning on Reddit and confirmed, "it’s not the device that exploded, it’s the chemical on the inside that has done it".

Bunnings advises customers to follow all instructions

Others suggested there might have been residue still inside the device from another tablet, with the poster confirming "I had an almost disintegrated tablet in there and put a fresh one on top. Maybe the original one was a different brand". They said it was "scary and really unexpected".

Speaking to Yahoo, Jen Tucker, Bunnings Director of Merchandise said, "We take the safety of the products we sell very seriously and we work closely with our suppliers to ensure the products meet relevant safety standards and regulations.

"As always, we encourage customers to reach out to us if they have concerns about an item purchased from Bunnings and that they carefully follow all advice and instructions on the product label."

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