Silver granite patio brown marks

[cindy]

Hi I have recently had a patio laid. After a few weeks irregular light brown marks have appeared on some of the slabs. I have been told it is not rust. Any ideas. The patio was laid in 2 areas . The area next to the house is fine but the bottom of the garden patio has these marks.How can i get rid of them?

[Tony McC]

We'd really need to see the paving, and the marks, before being able to advise appropriately.

[cindy]

I will post photos as soon as I can . Thanks

[Old Codger]

Is the paving affected next to a lawn or flower bed?
My guess, obviously without seeing pictures, is that as its the bottom area that only has the brown stains it could be
fertiliser as this contains ferrous sulphate.

[cindy]

https://photos.app.goo.gl/YOHET3FKOvkt27dO2

[cindy]

The patio affected is at the bottom of the garden and backs on to next doors who have a large tree. The patio next to the house which was laid on broken up stones of old patio is not affected. Thanks

[RAPressureWashing]

From the photo just looks like leaf tannin stains were there leafs etc sitting on the paving for a few days? if yes, very easy to remove, have a look on the main site, http://www.pavingexpert.com/stains.htm
use the mix for the berries & fruits stain removal.

[cindy]

No,was like this before leaves fellx

[RAPressureWashing]

Okay, have you used a grass fertiliser near the paving?

[cindy]

Yes, think my grass was treated not long after paving laid. Do you think that is it.... And if so any ideas what I can do? Thanks

[RAPressureWashing]

It could well be that then, fertiliser staining, the colour of the stain is about right from what I can see, yes they can usually be gotten off, please don't put anything on it for now. The thing is you really need a low-speed rotary machine and sometimes have to test a couple of chemicals to see what one will get the stain out, normally I'd say use X but you have to be quite quick with using it as that can damage if not careful. Where about's in Kent are you??

[Old Codger]

Diluted Lithofin Bero will get rid of fertiliser staining although it is always best to treat the whole slab. Only do test one slab to start with.

[cindy]

Thanks for all your replies will try this when weather improves and if they come up clean I will then seal it. Will sealing prevent future stains or should I avoid grass fertilizer?

[RAPressureWashing]

Don't even think about sealing this side of spring, it is now to damp & cold to seal. Sealing will stop staining for a while, but you still have to remove whatever it is that has/might stain, just don't magically go away, re the grass fertiliser, yes feed the grass as needed but try not to get any of it on the paving, as it will stain, it is once the feed (pellets or sand) get wet that it starts to work and if it is on the paving then that's when the problems start.