I generally brew nothing under a 1.050, but just recently brewed a 11 gallon 1.032 berlinerweisse currently fermenting. At the start of it all, was was concerned about fly sparging 10 gallons + of wort through such a shallow grain bed (12 lbs of grain). Specifically, I was worried about hitting extraction gravities dropping below 1.010 and/or PH (which I dont have a monitor for). I brewed the batch despite these concerns and sure enough I hit my numbers as expected, but the final run-off was down to 1.007 (damn it!).

This is an issue I usually never have to worry about since I artificially set my mash efficiency ~4% lower than I actually acheive. By doing this, I collect all my sugars by the time I reach 10 gallons of wort collected then top off with extra filtered water to reach the desired ~13.5 gallon pre-boil volume. Sure I'm waisting a little bit of grain, but never have to add DME. If the conversion/sparge is less efficient than usual, I just keep sparging to full boil volume. Sparge gravity usually never gets below 1.020 or 1.015.

My thoughts on the low gravity brew would be to calculate the recipe for a 5.5 gallon 1.064 brew (ends up being the same amount of grain), collect the 5.5 gallons and then dilute down to the full 11+ gallon batch volume prior to boil. I know the system won't have an issue with sparge gravity dropping below the 1.010 gravity at the 5.5 gallon 1.064 gravity level.

The real question is what reasons should I not brew any future low gravity beers as described above or if the theory is fine and I should proceed with no worries.

Thanks,

Unless you have have a philosophical objection, or your system doesn't handle them well, a batch sparge will help avoid oversparging...

I think you are worrying a bit too much about oversparge. As long as your sparge water doesn't have to high of ph i don't think you will notice any astrigent characters. Secondly if you want to do the 5.5 gallon sparge and then top up with water that will work just fine too.

To avoid any possible issues with astringency from over-extraction, you could always run a no-sparge mash, then top off with water to hit your boil amounts.

...or just batch sparge.

love

g

+1 to the grod

Yeah I would do the no sparge method...

I definately prefer the fly sparge method since it gives you much closer control of your Original Gravity making it possible to hit your target gravities/volumes easily. I am thinking that collecting the 5 gallons of 1.064 wort then diluting down to the 10 gallons of 1.032 wort would be my best option ... plus would save on time spent sparging. I guess the main concern would be if adding the 6+ gallons to dilute would screw up the pH? No pH meter here so I won't know if that is a real issue.