I’m converting from BIAB to a 2 vessel continuous sparge system.
I understand that I want to sparge at a rate equal to lautering to keep a few inches of water on top of the grain bed. Should I keep a submerged grain bed even when approaching the target pre-boil volume?
Example: assuming I mash with 9.5 gallons of water (approx. 1.5qt/# of grain) and my target pre-boil volume is 14 gallons:
Do I continue to sparge to keep a completely submerged grain bed until a full 14 gallons are collected leaving 9.5 gallons of water in the mash tun? (seems like a waste of water…)
Or do I stop adding sparge water and drain water through the grain bed so that there is minimal water left in the mash tun by the time 14 gallons are collected in the boil kettle?