Recommendations on cleaning patio slabs

Hi guys.

We had a section of our garden renovated and left an area with slabs to put garden furniture.

We used 600x900 slabs and at the time I noticed they were quite dirty, almost like something had been spilt on them, I mentioned this to the builder who told me it's normal and they would "weather" and eventually disappear.

It's been 8 months now and I've seen no change, Ive tried power hosing but it won't go away. Has anyone experienced this before? If so what did you use to remove it?

The dotted marks lead me to believe that they were created while the tiles were stacked prior to use. Have you tried scoring a mark in one corner, to confirm that it only affects the surface? You could also try treating a small patch with various solvents, brick cleaner and so on.

I had a problem with surface algae which result in unsightly black spots, and I used something called Patio Black Spot Remover. Frightfully expensive but it did the job. You might like to ask the makers if it would help in your case - they're on 01252 759931, www.patioblackspotremoval.com.

BTW, the standard of laying and grouting doesn't impress me.

Thanks for the suggestion, I'll send them a message and see what they come back with.

Yes, I noticed when I was power hosing I dislodged some of the grouting, not a good sign.