A couple of questions on AG

[BrewBoy]

Last night I did my second AG brew following the B2B2 rules. I will post some pictures in the Brewdays forum later. It did raise a couple of questions though because I ended up with quite a bit less than planned. I think I know how to fix it and its all trial and error at the moment but want to get it almost spot on while I’m doing mini mash before stepping up to 40 pint brews.

1. How do you plan to finish on your planed brew length? For this I’d like to know how much water the grains retain? How much is generally lost to boiling? Do the hops soak up a lot? Do you top up after the boil?
2. How much sparge water is required per kg of grain?

Thanks for you help.

 

[Dave1970]

bearing in mind that I don't to this quite as accurately as I could....

The key to hitting final volume for me is the pre-boil volume. I know with my boiler and an average amount of hops I need 30 ltrs at the start of boil to end up with 23 ltrs in the FV. For a 60 min boil it'd be 28-9 ltrs. For a very hoppy brew I might go to 31 ltrs. This will vary according to your setup so an element of trial and error is needed to arrive at this point.

I just mash at 2.5 ltrs/kg and then sparge until I've got my desired pre-boil volume, checking the gravity to make sure I haven't gone below 0.990 & risked starting to extract tannins. If I fell below 0.990 before I got to my desired volume then I would fall sort of the target volume....but this hasn't happened yet.

 

[Hawks]

Agree with Dave, it can take some time as you learn dead spaces etc as well...

for absorption, IIRC it is around 1 litre per KG of grain

hops do absorb a lot - I forget how much now though and work like Dave in that if I am using a lot of hops I add an extra couple of litres - maybe around 1 litre per 200g of hops :hmm: The correct ones are out there and I used them in my calculations so I am sure someone will be along and post the accurate ones. :thumb:

 

[Aleman]

hops do absorb a lot

Yep around 1.5 litres for every 100g . . . and IIR they displace around 6L for every Kg of hops

 

[Hawks]

Thanks Aleman - I was miles out..