Perhaps I've simply missed it somewhere, but I've never read anything describing why a batch sparger's pH won't generally change much (Denny Conn has said that he's measured it..though he lives in oregon and may have low mineral water) when they sparge, and thus there's not nearly as much concern about tannins with batch sparging. Yet, there seems to be with fly sparging (I say there seems to be, since I've always batch sparged.). Does anyone know the reason for this? Is it simply the prolonged contact time that's involved in fly sparging that causes the pH to rise more? I know the mash acts as a pretty decent buffer, do buffers become less effective over time?