[Eric H]

I have just cleand a swimming pool and the client ask'd me to try cleaning the Indian slate around the pool. The slate is pitted with black marks, and no ammount of flatbed or turbo lance would move it.
He has tried sandblasting one or two slabs and this worked very well but took the best part of fifteen min.and there is 90M to do. Is there a chemical I could use? or any ideas please.

[David Lauder]

Eric

Slate - especially the Indian and Chinese stuff - can be quite a delicate material and so the cleaning should take this into account. Have you any idea what the marks are? I would find out as much as you can about the nature of the marking and then decide on what to do - but be very wary of simply throwing chemicals at it as you may end up with more problems than you started out with!!

Kind regards

[peejay]

Hi,  the black marks on the slate is probably a special fungii called "black spot" it can only be removed using a special acidic solution, this is normally available from shops that sell swimming pool chemicals, i am speaking from my experience of cleaning same in many swimming pools in australia, however may be called something different here, but i would be very surprised if this wasnot the problem,  good luck to you

peejay

[dougster]

contact me and ill tell you how to fetch them back to brand new look