Removing Black Spots On Paving Flags

[Barsel]

I have just had my paving flags Karchered but the flags are still full of black spots. Is there an inexpensive way to get rid of them?Thanks.

[bookbinder]

Try a bucket of water with a shot of washing-up liquid in it, applied with a stiff yard brush.

[roslyn251254]

domestos and a stiff brush

[teacake44]

Its always been a big problem, and of yet seen a answer for it. The only bit of success I've had is to spread neat bleach all over with a brush, lots of it, bleach is cheap, and leave it to soak over night. Cats won't come near it because of the strong smell.

[calmck]

Can you get muriatic acid or a product containing it but you have to be careful with run off, or a good patio cleaner

[ummmm]

Brick acid.