Question

Jet washed the patio and managed to get a lot of the dirt away but it’s far from what used to look like when it was new. Any suggestions on how I can get rid of the black spots? Would bleach and a stiff brush do the trick? I have got two cats so I’m bit nervous about using chemicals but the jet wash won’t lift any of the remaining dirty and I’ve noticed it already started chipping the slabs so don’t want to overdo it. Thank you

Answer 1

Neat washing up liquid, brush till a thick white foam (no water) and leave it to work its magic, then rinse! I was shocked how clean it brought my slabs up!  

Comments

@linseed I’ll try that tomorrow! Thank you

Answer 2

Soda crystals and hot water throw it over and leave. Really works well x

Comments

@ignitron I’ve some at home so will definitely try

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@ignitron thank you

Answer 3

Jet wash again I think

Comments

I tried going over again but made no difference apart from chipping the slabs  

Answer 4

Bleach is a chemical. I use Spray & Leave on my patio, no scrubbing needed and once it’s dry it’s safe for pets and children. It continues to work for up to six months.  

Comments

@myogenic546 this is what I use saves all that scrubbing

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@cockerel it’s brilliant, saves time and effort.  

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@myogenic546 thank you. I love that doesn’t need any scrub!  

Answer 5

Bleach washing power water &a stiff brush will come up like new

Comments

@galactometer bleach will make the stones white

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@enchiridion lf they are coloured it won't mine were fine

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@galactometer ok only I had green stones before I used bleach. now grey but no green slime

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@enchiridion I’d love if they did come up white as they suppose to be white. if only I knew they would get so dirty and discoloured when we picked them up!  

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@emetic My path slabs always come up like new &they are white

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@galactometer perfect, thank you!  

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@emetic yes wet the slab first . (I do it when its raining so my cats dont get bleach on them) leave the bleach on for ten to fifteen minutes then hose the lot down. while scrubbing the dirt of. i do this at least three times a year. as my slabs dont get much sun.  

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@enchiridion thank you

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@emetic your welcome

Answer 6

Black spot remover

Answer 7

Domestos let it eat in  

Answer 8

Wet and forget

Answer 9

I'm sure a few more goes it will be fine.  

Answer 10

There are natural algae patio cleaners out there. I have heard of them but not used yet. We will do ours in the Spring.  

Answer 11

Maybe try some bicarbonate of soda and a stiff brush it works on grubby pans etc.  

Answer 12

Wet and forget every time it rains it reactivates it

Comments

I got mine from qvc but cos co is selling it now

Answer 13

Brick acid and a brush then jet wash it off and should come up like new

Answer 14

I used patio magic on my jet washed slabs. Mix up, sorry on and leave it to dry. Not immediately noticeable but it will clean it up a d keep it clean.  

Answer 15

Don’t bother with bleach or washing up liquid, it doesn’t work. Ours is the same, I’m waiting for a dry day to do wet and forget

Answer 16

Is this Indian stone? I'm about to have some laid contemplating a sealer as the more u jet wash the more holes you put in for dirt to get ingrained

Comments

@comparison1467 I’m not sure what type of slabs it’s I’m afraid. When he designed the patio, we went of the palest slabs and stones we could find. if only we knew they would get so dirty and discoloured!  

Answer 17

Wet & Forget it's brilliant the black mould spots take longer to go than algae but it continues to act and need more than one treatment to get all to go but then use twice a year maintain. No harm to pets or wildlife once it has dried. Also kills moss.  

Answer 18

Same here today

Answer 19

Algicide like Wet and Forget, or Algon, safe for pets and wildlife.  

Answer 20

Impossible. They are in the stone and coming up from underneath. I have the same problem.  

Answer 21

This product is truly amazing!  

Answer 22

Vinegar preferably the white variety and brush it in . x

Answer 23

Be really careful with the cats, if the cleaner has Benzalkonium chloride in it then you need to make sure it's fully rinsed and Dry! Our cat walked over ours still wet then groomed herself and ended up with a tube in her throat and in hospital. Other than that we used jays cleaner. Just keep them clear and let it dry

Answer 24

Patio magic- pet and environment friendly

Answer 25

Try this you dilute and spray on a dry day it keeps working for few month its brillant

Answer 26

I bleach mine. cats don't go near it

Answer 27

I use Zoflora on mine

Comments

@hachmann zoflora is a disinfectant not a cleaner. Does it remove the stains?  

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@ignitron it seems too! i did have the hump that day so was scrubbing bit harder! lol x

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@ignitron i used a hard bristled yard broom and plenty elbow grease! lol x

Answer 28

Sodium Hyperchlorite. You’re welcome.  

Answer 29

Looks like you need a stronger power washer.  

Answer 30

Chlorine is the way to go it will work wonders and pressure wash off let dry then seal it