Guys, please stay away from OO. Write me offlist I you want to know more about my sad experience with my USB4000 -- the instrument is OK but the software royally sucks, rendering the instrument virtually useless. / Roger > None of the more flexible instrument are. To measure down to 1000m or > into the UV needs something like an Ocean Optics module, which start > around US$5000. > > Graeme.