My first 3 AG brews have all had an aftertaste that wasn't overpowering, but it masks the hops, and wasn't meant to be there. It's not instantly identifiable as buttery or green apples, or any of the other descriptions. Even the LHBS couldn't put a finger on it.
The batches have been a mixed bag of success, one went fairly straight forward, the other two either mashed high or ended up with a leaky chiller.
I fermeted/bottled batch 1 & 3, and they had similar taste coming out of the fermenter, despite being different reciepes and different f**k ups. Batch 2 was fermented elsewhere, and kegged + bottled, but has similar issue.
Meanwhile my mate (topher) using much the same gear has had better success.
So, I was thinking about what was the same for my brews and different for his. And Whirlfloc stood out as one of the few things consistent in my batches and not in his at all.
1 - Fat Yak clone
Mashed high, cubed, pitched with rehydrated US05
Bottled
2 - Fat Yak clone
Used carbon filtered water, brewed at a different house (same Sydney water Dam probably).
Mashed at 65-66, cubed (different cube), fermeted at topher's place (different FV/fridge)
Some kegged and some bottled
3 - DSGA
Mashed at 64-67, diluted with chiller water though, pitched with rehydrated US05 in same FV as first batch
Bottled
Don't really have time/money for changing one variable at a time, so yesterday I skipped the Whirlfloc, used a new FV, checked the chiller wasn't leaking 
and just sprinkled the yeast.
Time will tell if this 4th batch works out, but I wondered if anyone else had issues from Whirlfloc.
