I have read various articles/posts about storing harvested yeast/slurry (both frozen and refridgerated), and noticed some concern about fluctuating temperatures harming the viability of the yeast. I know the temperature controller I have on my Beer Fridge (converted from an upright freezer) can fluctuate 4 degrees. Articles that discussed freezing yeast (I don't do this yet) say that a frost free freezer should not be used because the yeast wiil alternatly freeze and thaw, freeze and thaw.
To the point of this post. I was talking with the head brewer at a local brewery (Cheers to Highland Brewing in Asheville, NC) and he said to store the slurry in an ice bath in the fridge. This will keep refridgerated samples at a more constant temp. This hit me as such an easy solution. I'm sure many of the more expirienced brewers do this, but I thought I would throw it out there for us "newbies".
I'm not sure if you could over come the pitfalls of a frost free freezer by freezing the sample in ice.