Harvested yeast...color?

[sundog14]

I harvested (top crop) some WLP530 (Abbey ALe) from a batch of pumpkin ale recently and am confused as which layer is trub and which is yeast. As far as I know, the yeast will tend to settle towards top and tends to be lighter in color than the trub. In the photo (attached), the lighter layer is on the bottom. I would like to try to decant off some of the trub. Any guesses as to which layer is the trub?
On a related issue (same pumpkin ale), after 3 days of open fermentation I racked to a 5 gallon carboy for secondary.Under the carboy, I had a heating pad at low. I sometimes do this to give the wort/beer a bit of a "boost" at this point and leave the heat pad on for a couple of hours. However it was on for about 18 hours and the temp went up to ~ 82F. The airlock is barely bubbling. I'm wondering if I killed most of the yeast and should pitch some to insure carbonation after bottling. FYI, the wort went from 1.055 to 1.011 in about 30 hours in primary (open).
Thanks, tom

 

[kristiismean]

nice, 30 hours!

still has cleanup.

yes, the yeast in on the top part, the hops or additions fall first as the yeast propagates then drops.

It possible the heating pad did hurt the yeast, it all depends on the ambient temperature. i figure if the beer is 82, the room is 72, then the power output is blah blah watts, and so maybe the bottom was 105 or higher? I do not know what temp yeast is officially "dead" (well, 160 for sure)

 

[sundog14]

Hello kristismean,
Thank you for your reply.
Yes, I guess the real question is "how hot did the bottom of the carboy get to"? I can;t answer this but I can imagine that it was 105 or easily more. For this reason I have decided to rack the batch again. I think that this is preferable to letting it sit on the yeast and trub cake (looks to be ~ 1/2")for another two weeks. I'll rack on top of that yeast (in pic) that I top-cropped from primary. I took a taste and SG test this morning: taste OK, SG= 1.011 (no change). My main concern is that I don;t have a cylinder of CO2 to pre-fill the carboy.