Reusing yeast

I know I haven't posted in a while, school has really been getting to me. Not so much so as to prevent me from brewing, or enjoying good brew, just so much so as to prevent me from posting.

I have re-used yeast a few times: When I reused yeast, I siphoned the beer off of the yeast, and then covered the carboy with aluminum foil. I bottled that batch of beer, and then brewed another batch. When that batch was ready, I put it in the carboy. That was a time span of about three hours between pulling off one batch of beer and replacing it with the second one. I have re-used the same yeast twice (a total of three batches of beer on one packet of yeast).

I started with a strawberry pale ale, then a chocolate porter, and finished it with an imperial stout. The strawberry flavors (I put them in after the boil, and removed them prior to putting the wort in the carboy) made themselves known only to the more discriminant of palates. The chocolate flavor did carry over a wee bit into the stout, but obviously there were no hints of the strawberry flavor.

This is a picture of the different sediment layers that resulted from the reuse of yeast.