Cleaning Concrete Slabs

[Lillibet123]

What is the best way to take the black mould on concrete slabs off and get the weeds out of the small places between slabs.

[Prudie]

Powerwash the slabs and something like Pathclear or weedkiller for the bits inbetween.

[Old_Geezer]

Not sure about best ways, but a jet pressure washer works well even if clearing off the stuff you shoot out of the 'small places' means you have to keeping going one way towards the drain.

[Sam1960]

HSS have a number of jet sprays that should do the job

[Kgrayz]

power washer and bleach

[March-Hare]

Cheap pine disinfectant and a stiff broom and rinse of .... More effective than jetting alone

[theshedman]

I would say use the method Prudie says with putting down the Pathclear first as this will kill the roots of the weeds and not just rip them out as the power washer would if you use this first. Then they won't come back as quickly.

[Gizmonster]

For the weeds, as already suggested, use a good weed killer.
for the mould, I highly recommend a product that I recently got recommended "Dairy Hypochlorite". In all the times I've power washed my patio, there's always been a stubborn green mark, where the water runs off onto the steps .... no amount of power washing ever removed it.
I used this Dairy Hypochlorite and I know it's a cliché, but my patio looks like new, it's never looked so clean .... and the stubborn green mark - gone without a trace :)