ok... answering my own question

http://www.vinylengine.com/turntable...ic.php?t=38459

but shows how easy it is to stop with mis-information.

'Alex' in post two says de-minerlised 'fine', but if you go down to 'Guy's he seems to give a fuller explanation of why it isn't ... . Probably (in the sense that the stuff I've bought off amazon may well use additional processes that deal with the dissolved ionic goobers). Sigh.