I'm brewing my first batch with a brooklyn brew show all-gain kit. I skipped the airlock and left the blow-off tube in place in a pot of bleachy water. It's been there for the past two weeks.
Today, I go look at it to start bottling and I see mold growing on the water that the blow-off tube was plugged into! I guess the bleach evaporated..
Is the batch ruined?
And to avoid this in the future, I suppose I should just re-up the bleach every so often?
It's not at all ruined. The airlock is working exactly as intended. Unless there is a growth of mold all the way up the blow-off tube and into the fermentor, you're fine.
It's not so much that the bleach evaporated as it was denatured by the copious blow-off material. You don't need to "re-up" on bleach (you really don't even need bleach) so much as discard that nasty-ass blow-off water after the ferment is far enough along that the blow-off tube is not really needed.
