Deck scrubber and bleach?

If you use patio cleaner and a hard brush it should come up much better than it sounds takes a bit of elbow grease but ours came up quite well..

Hire a pressure washer.

I used to have pink sandstone flagstones round one of my previous houses. The house martins nested in the eaves above. I used a deck scrubber and hot water with bleach. It brought off the mess beautifully, but I made the mistake of scrubbing them wearing dark denim jeans! They had littlecwhit spots for ever afterwards. ?

Yes, diluted bleach !

Do you live near the Hants/Berks border? If so you can use our pressure washer. Something else that works are soda crystals, sprinkle on, dampen, leave for a day or so then attack with a deck scrubber. Knackering but effective.

I use the outlet hose from the washing machine to catch the hot water after a wash, in a big bucket and use a deck scrubber on the patio. It's free and effective if you have used biological detergent. Might take a couple of goes, and depends how big your patio is, but it's what I do and it works for me.

Thanks everybody going to give it a go in wellies and old clobber.
Alima thanks for the kind offer but we are in Staffs .
Mrsmopp I think that's a great idea, will use it to keep patio clean once I've scrubbed with Soda crystals, patio cleaner and/or bleach.
And if I'm defeated a pressure washer!

Was born in Stone, cherry x