Cleaning patio slabs

[alex812]

Have some paving slabs that have gone black with mould. Cleaning them is beyond my pressure washer. Trying to establish rough price/square metre for professional cleaning but anyone I contact wants to see the job. Can anyone give me an idea of price?
Alex

[saechunu]

Await a forecasted dry spell, then using a pressure sprayer with a wand, thoroughly spray your pavers with a 10:1 diluted solution of BAC-50 from Bonnymans:
https://www.amazon.co.uk/BAC-50-Benzalk ... B00BWRECXG

Several weeks later hose them down and there is every likelihood the algae discolouring your pavers will be totally gone.

Repeat once a year etc.

[stewamax]

The post made me wonder whether dilute benzalkonium chloride would also remove the green lichen from rough-wood garden fence panels? I have been re-staining them along with the smoother-wood panels that don't attract green lichen, but perhaps this is a better answer.

[saechunu]

The post made me wonder whether dilute benzalkonium chloride would also remove the green lichen from rough-wood garden fence panels?

Yes; a weaker solution than mentioned above should work. Also, my experience is if you happen to catch adjacent shrubs or climbers with bits of spray they're unaffected.

[stewamax]

Worth noting that benzalkonium chloride is dangerous to cats; after contact they tend to lick their paws and thus ingest it - with a severe and occasionally fatal reaction.

[csearle]

Worth noting that benzalkonium chloride is dangerous to cats; after contact they tend to lick their paws and thus ingest it - with a severe and occasionally fatal reaction.

Don't give people ideas!