Cleaning soap scum off the shower is easily one of the most soul-crushing household chores. You can scrub until your arms ache and breathe in harsh chemical fumes, only to watch that cloudy, stubborn haze reappear after the next shower. It turns out one of the most effective solutions sitting on Bunnings shelves isn’t in the shower aisle; it’s tucked away with toilet cleaners.
One Shot Thick, a concentrated $16 acid cleaner originally formulated for descaling toilet bowls, has quietly gained a massive cult following for its ability to melt stubborn shower-screen soap scum and hard-water scale. Intrigued by the viral reviews, we put a 1L bottle to the test on foggy shower glass to see if it lives up to the hype, and the results were impressive.
KEY TAKEAWAYS
- One Shot Thick is designed for toilets, but its heavy-duty sulfamic acid formula melts through stubborn shower screen soap scum too
- The thick gel formula clings to vertical glass surfaces
- Budget-Friendly: At just $15 from Bunnings, it delivers professional deep-cleaning results
- Safety First: Always wear waterproof gloves
- Surface Rules: Safe for glass and sealed tiles, but strictly avoid using it on marble, natural stone, unsealed tiles, brass, or corroded metal fittings
Why is everyone obsessed with One Shot Thick?
TikTok user Trace was thrilled with the results, calling One Shot Thick the best thing she’s ever used on shower glass. In her video, she showed how it wiped away eight years’ worth of stubborn build-up in minutes.
Initially designed for descaling toilets, One Shot Thick contains sulfamic acid, a heavy-duty ingredient that cuts through hard water scale, calcium buildup, soap scum, and other stubborn stains.
It also has a surprisingly mild scent—a soft floral fragrance rather than the harsh, nose-burning fumes you might expect from a heavy-duty cleaner. Michelle Moore, who works with the company behind One Shot Thick, says it’s about 80 per cent milder-smelling than bleach, so you don’t have to hold your breath while you work (though good ventilation is still recommended).
It’s not just for toilets
This hard-working cleaner has earned fans well beyond the toilet. Professional cleaners and TikTok users alike say One Shot Thick makes shower glass sparkle, brings stained sinks back to life, tackles grimy bathtubs, and freshens up most sealed tiles—all without hours of scrubbing.
“It’s one of the few products that actually works.”
Michelle says, “It’s thick enough to cling to vertical surfaces, giving the formula extra time to dissolve deposits and grime.”
She adds, “One Shot Thick removes the scale and stubborn buildup in toilets that a regular brush just can’t shift. This is a common problem that frustrates many people and can be quite embarrassing. It’s one of the few products that actually works.”
“Professional cleaners have started calling it a ‘cleaning hack’ because it also works on shower glass. That’s another spot where grime and hard water deposits build up and feel almost impossible to clean properly.”
Is it safe to use on glass?
Although made for the toilet, Michelle says One Shot Thick is safe to use on glass. Avoid scouring pads, as they can scratch. Instead, use a soft sponge or brush to scrub, then rinse thoroughly and gently.
Can you use it on grout?
Similarly, she says it’s safe to use on grout, but it shouldn’t be left to sit for too long.
“We recommend limiting the contact time on grout to the duration needed for cleaning. Rinse off after use and do not allow the formula to dry on the surface,” says Michelle.
On white unsealed grout, rinse off straight away to avoid blue staining.
What about mould?
You might be tempted to tackle mould with it, but experts advise against this approach.
Michelle says, “We recommend using a specialist mould cleaning product to remove mould because blue staining may occur on unsealed grout.”
How to use One Shot Thick (without ruining your bathroom)
Protect yourself first
Always wear waterproof gloves to protect your skin from the sulfamic acid in the formula. If there’s a chance the cleaner could splash—such as when scrubbing with a bristle brush—put on safety glasses or goggles to protect your eyes. When working in enclosed spaces, such as showers, ensure good ventilation by opening a window or switching on the exhaust fan.
Apply it undiluted
Pour or squeeze One Shot Thick directly onto a soft sponge. I’ve used a microfibre cloth. The product’s thick texture helps it cling to vertical surfaces, such as shower glass or toilet bowls, providing more contact time to break down stubborn deposits.
Scrub gently but thoroughly
Work the product over the surface in small sections, applying light pressure to loosen soap scum, calcium build-up, and limescale. On glass, use a sponge or soft brush to avoid scratches. For tiles and grout, limit contact time to prevent staining, especially on white unsealed grout.
Rinse with cold water
Once the grime has lifted, rinse the entire surface thoroughly with cold water. This stops the cleaning action, removes residue, and helps prevent streaks. For showers, use the showerhead to flush away every trace of the cleaner.
Repeat if necessary
In cases of heavy build-up or older stains, a second application may be needed. For the best results, clean in stages rather than leaving the product on for an extended period
Avoid using on marble, natural stone, unsealed tiles, bare aluminium, corroded chrome, coated aluminium frames, brass, or coloured coated metals.
The verdict: Is One Shot Thick worth the hype?
Rating: 4.5 / 5 Stars
If you’ve been fighting a losing battle against cloudy shower glass and baked-on soap scum, One Shot Thick is absolutely worth the $16 investment.
While using a heavy-duty toilet cleaner on glass may seem like an unorthodox risk, the thick sulfamic acid formula dissolves hard-water mineral deposits without requiring back-breaking scrubbing.
What worked
- Zero muscle power needed: The gel clings to vertical glass panels, letting the chemical formula do 90% of the work.
- Mild scent: Unlike harsh bleach or ammonia sprays, it leaves a surprisingly light floral fragrance rather than overpowering chemical fumes.
- Instant visual transformation: Rinsing the glass with cold water revealed crystal-clear results in under five minutes.
What to keep in mind
- It is an acid product: You must wear gloves and ensure your bathroom is well-ventilated while using it.
- Not for daily use: Keep this as your secret weapon for deep cleaning or seasonal Spring refreshes. It’s heavy-duty stuff, so don’t leave it sitting on tile grout for long periods, and avoid natural stone entirely.
For less than $20 at Bunnings, it delivers deep-cleaning results. If your shower screen hasn’t seen the light of day in months, grab a bottle on your next trip to Bunnings and see what the fuss is about.
Where to buy
One Shot Thick is stocked at Bunnings in 1L and 5L bottles. Just be sure to check the website before you dash out, as this sought-after cleaner is flying off the shelves. It can also be purchased on Amazon.
For toilets, you can use One Shot Thick regularly. For showers, it’s best as a deep-cleaning solution whenever you see limescale or stubborn build-up in hard water areas.
After cleaning shower glass or tiles with One Shot Thick, follow up with Clean and Bead from Peerless JAL. It leaves a protective film that slows buildup and even prevents fogging.
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