when we al started learning stuff about beer, someone said that that the differences beetween lagers and ales was that in lagers there was bottom fermentation - that is, instead of the traditional krausen, there would be some kind of "underwort krausen".
but the thing is: from what i've seen in my lager fermentations, that's not what happens. The krausen is still there, top fermenting like any other of my beers.
so the big question is: are the lagers yeasts we're using ACTUAL lager yeasts (s. carlsbergensis) ou ale yeasts (s. cerevisae) modified to ferment between 50 and 60 degrees F with no estery effects?
(just so you know: the only lager yeasts I have ever used are fermentis' dried ones: s-23 and w34/70)