I have seen it written somewhere, but for the life of me cannot remember, will have a look though.
I found this on Televue's site which sums up optics cleaning, so we are both right. Have a read.

http://www.televue.com/engine/page.asp?ID=143

As a footnote, the guy I bought my Tak off told me NEVER to use alcohol based cleaners on my objective, he worked at a university where the guy who cleaned all the microscope optics gave him that advice. So who does one believe.

End result dont clean too often and always blow dust off 1st and do it in a clean environment. Oh yeah this is only for refractive optics, it is a whole new ballgame on mirrors.