Pre-boil est. is spot on but Post-boil is not?

[^Tony^]

Hmm.. So just calculate for a thinner mash and do away with the extra sparge step to top off. May take a bit more practice to get the right volume, but I'm open to that too. It may only work out on my bigger kettle though.

Thanks everyone..

I do BIAB with a 55 L (15 gallon) kettle so I CAN to do a full volume mash. That makes a difference in the volumes but it may be as simple as you say. Calculate for less mash volume then just top up to your pre-boil volume. Keep in mind your gravity at the end of a partial volume mash should be ABOVE your target pre-boil volume because you dilute it when you top up.

The amount of grain you use will also effect your volumes due to absorption. I use about 5-7 kg (11-15 lbs) every brew so I can keep things at a pretty close constant. (It took me 3 brew sessions to make sure I had all the volumes to where I liked the outcomes.)

In the end it just takes repetition and some good notes and you will nail it for your equipment and process...until you upgrade equipment

 

[Mark Farrall]

I'm another full volume masher. I just prefer the simplicity and I don't notice much of an efficiency hit.

Though I think there's probably a point where the mash may be too thin. For my low ABV beers (I do a few around 3% ABV), I'll top off with water. If I was low I'd leave the bag in the kettle, but haven't needed to do that often. Currently I try not to go thinner than 5, maybe 6, litres per kilo of grains.