How to clean concrete tiles?

[TopFlatTroubles]

Apologies if this is the wrong place, I'm not sure if it's DIY, Housekeeping or even gardening!

We are in a top floor flat and have a balcony laid with concrete tiles. They look revolting and I don't know the best way to clean them. I'd love to be able to use bleach on them as I think this is probably the easiest way but.... we live on the top floor. I'm not allowed to use anything corrosive on the balcony, nor any kind of plant/weed/moss killer i.e. anything nasty in case it damages the lining of the balcony or drops through to the neighbours below. Can't use a high pressure thing because it will damage the tiles.

Which leaves me with the floor cleaner I use on the bathroom tiles or washing up liquid plus a scrubbing brush and both seem pretty ineffective. Is there a trick I'm missing? How do I get them clean?

We had those horrible things too, but took them up and replaced with slate. Not on a balcony though.

How are the slate weather wise? Do they cope with extreme conditions?
It's on the list of things to replace, but will be at least 5 years before we can afford it!

The slates work well, but they did turn bright green over winter. I found watering them with Patio Magic from Wilko and leaving it to dry for 2 weeks brought them back to new looking.

They look like paving slabs rather than tiles. I think they are damp, which darkens them and encourages mould and black mildew.

There is a product called "wet and forget" you can order online that will kill it, you dilute and water it on. I don't know if Patio Magic is similar

You can use a soft sweeping brush to remove dirt and any organic matter such as leaves.

Don't use a stiff brush which will abrade the concrete and cause unending gritty dust.

@PigletJohn not sure of the difference between slabs or tiles? Is it just the thickness? Then yes, they're probably slabs! They are dark as it has just rained, but they look just as bad when they're dry. I didn't realise that about the type of brush, so will get a softer one. Thanks.

Both patio magic and wet and forget say they kill the gunk; neither say if they're safe to use in balconies though. Or if it's dilute enough, it shouldn't be a problem? Also for the DC to play on?

Is painting them an option?

Our friends once got white spray paint on tiles like this in their patio and spray painted a Moroccon pattern on them like you see on modern black and white tiles. Did well to disguise the condition.

Sorry meant to say using a stensil