BIAB.....How much water to start with?

[Duxuk]

My BIAB bag material arrived today as I was leaving, then when I got back my new stockpot of 32l (it's a big un!) had been left in a safe place. I have everything else I need from doing extract and partials, so Monday would be a good day to do my first AG. I'm not going to be too ambitious with the volume and will do 15l, as I've been doing recently.

My question is, how much water should I use for my mash to give me 15l. I will be using 3kg of Maris Otter plus 200g crystal and a total of 70g of hops in the boil.

 

[bunkerbrewer]

You won't know for sure until you make a few brews, so record your water volume at each stage (pre and post boil, and how much you end up with in the FV).

A boring but useful job is to add an accurate amounts of water a few litres at a time to your pot, and measure down from the rim to the surface of the water. This will give you a formula you can use on brewday to quickly measure how much liquid is in the pot.

Anyway... how much water do you need? Brew length + grain absorption + evaporation + boiler deadspace + hop absorption

Complete guesswork: 15L + (3.2kg @ 0.5L/kg = 1.6L) + (10% per hour = 2L) + 1L + a bit for hops = 20L.

You might want to register on the BIABrewer.info forum and grab a copy of their BIABabacus. That's got a more sophisticated volume calculator than my attempt :)

Good luck with the first brew! :thumb: (and don't worry if you don't hit your volume or OG - it'll still be good!)

 

[LeithR]

Hi there,
The norm is something like 3L/hour evaporation in a boil plus the liquor absorbed/retained by he grain, for 3.2Kg grain etc... I'd go with another 2L.

So for a 90 min boil you are talking 15L+5L+2L=22L

You might have some dead space in your boiler which you will need to take into consideration. If its just an unmodified stockpot then there is nothing to consider in this case. Its when you add tap and grain/hop strainer you will need to consider this.

Have fun and let us know how it goes/went.

 

[Duxuk]

Thanks for the help. :thumb: Usefully my 32l stockpot measures 32cm inside depth, or 1cm per litre! Easy life. :

 

[rpt]

I use the BIABacus too and it makes it very easy. For my first AG I hit all the estimates very closely so it was a useful guide.

 

[rich27500]

I'd guess at losing 5-6 litres so 20-21 sounds a good start point. But why limit yourself? You can make 23 litres with a 19 litre stockpot.

 

[bunkerbrewer]

Thanks for the help. :thumb: Usefully my 32l stockpot measures 32cm inside depth, or 1cm per litre! Easy life. :

Are you sure it actually holds 32L though?! :)