Mould killer

Both Coles and woolworths have ceased to stock my favourite mould killer so I bought the one they now stock. Upon getting it home I read that the active ingredients are sodium hypochlorite and sodium hydroxide. In other words it is just a bottle of bleach posing as mould killer at $3 for 500ml. I can buy a 2 litre bottle of bleach for less than $2.
Wasn’t a pharmaceutical company just fined for giving different names to the same product and marking them up?
The mould killer I was buying contained no bleach and no sodium hydroxide and did an excellent job.
I’m returning the mould killer and buying a bottle of bleach.


Well, yes and no. Nurifen was taken to task by the ACCC because it was in effect relabelling the same product. The relabelled product was then marketed as being essentially more effective for a particular ailment.

This is possibly different as the final composition of both products (bleach and the ‘mould killer’) are likely to be different than the two Nurifen products which were exactly the same.

While I haven’t reviewed the contents of the products in question, I would suspect that the concentration of the active ingredients (sodium hypochlorite and/or sodium hydroxide) would be different, with the mould killer potentially also containing other agents to reduce chlorine odours or to improve spread-ability (such as a surfactant).

Also remember that sodium hypochlorite (bleach) only kills mould it comes directly in contact with. Which is good when using on non-porous surface like glazed tiles, but may not kill all the mould which has penetrated the grout between the tiles.


Choice recommends vinegar


Bleach does not kill mould, it simply turns it white so calling any bleach “mould killer” is a lie. The only thing that kills mould is clove oil.

Not quite correct.

Sodium hypochlorite, the active ingredient in bleach, only kills mould it comes in contact with. If the bleach doesn’t come in contact with all the mould, then it won’t be fully killed. It isn’t a systemic fungicide, which means it will travel through the whole of the living parts killing it all.

It readily kills mould on the surface of things, but won’t kill the mould which has penetrated materials…such as mould hyphae which has grown into grout or wood.

Hyphae is the filament or growing material (think of it like a root or stem in flowering plants) which makes up the mould/fungi and when one section of hyphae is killed, such as being in direct contact with bleach, any hyphae which is still living will continue to grow.

Google scholar has many papers which assess the efficacy of bleach/sodium hypochlorite on moulds/fungi.

It is also worth noting that weak/diluted sodium hypochlorite solutions is used within the food industry to sterlise food products which may have fungal and bacterial pathogens (including moulds).


Came across this and planning on using it to make my tiles shine …

Spray the affected areas – including tile, grout, painted walls, and any porcelain or ceramic surfaces – liberally with vinegar. Let it sit for one to two hours.

Scrub the mold and mildew away with a damp microfiber cloth. Scrub tiling grout or hard-to-reach corners and crevices with a stiff-bristle toothbrush. Rinse with water.

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Vinegar is a weak acid so on lime based grout it will over time remove some of the grout, some grouting materials these days can be silicone based caulking compounds and do not suffer this problem. This isn’t to say don’t use vinegar but just to be aware, vinegar has great germ killing ability and certainly on lots of household surfaces can do a great job.


It is used in a lot of bleach solutions these days to increase the pH (make it more alkaline) so that more of the chlorine is available in solution (ClO-). The reason it is used is because it is cheap, alkaline, and doesn’t react with the chlorine. NaOH (sodium hydroxide aka caustic soda) is also used to help manufacture bleach in the first place as a very high pH is needed to create more of the ClO-.

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What was the name of the brand you used to buy? Thanks in advance Anneke

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Mould Power. Uses bioflavanoids as the active ingredient and is chlorine free.


Apologies for the slow respond. Thank you John for that information. Anneke


John, I did find it online from the manufacturers.


I did contact them and they told me where I might find the product and I was able to get it from my local IGA. I returned the bottle of bleach ““mould killer”” to Coles for a refund


An article about just home bad mould can be to your health.