Working Out the Amount of Strike Water Needed to do a BIAB.

[Darren Andrews (Daza)]

If you were looking at doing a BIAB and wanted 23L in the Fermenter, how do you account for water loss? I see some say work backwards to work it out, but every system does vary some what and it is a trial an error way to do it, But what is the general water loss to grain is it 1 litre to every 1kg of grain? I have been Googling etc... but you guys know your stuff, and value your opinions. Cheers.

Daza.

[Sam DT]

34 Litres for strike and no sparge - if you want to sparge just reserve a few litres - that said you won't gain a huge amount of efficiency from sparging - most BIABers don't do it at all.

If you start with too much water you'll end up with a weaker wort and lower OG and a weaker beer. IMO you're best to err on the side of slightly less water (and a slightly more concentrated wort) because then you can always water down using a dilution calculator. Either way +/- a couple of points of OG isn't the end of the world.

Everyones figures are slightly different (unless you're using a standard system like the grain father). The only way to nail your numbers is to do a few brews and narrow down until you're hitting your target OG & volume.

[Darren Andrews (Daza)]

I think I would probably only do a sparge if I don't have the volume needed to start the boil...? yeah that sounds about right.

[Darren Andrews (Daza)]

Do you think it's worth going s mash out for 10mins or not worth it?

[Sam DT]

Worth it (at least with BIAB), you're going to have to heat your wort up anyway so just leave your bag in until you hit 75-77. Just dont' leave it in after then tho as you'll start extracting tannins and make sure you have a cake rack or something in the bottom to prevent scorching your bag on the bottom of the pot.

[Darren Andrews (Daza)]

Good tip on cake rack. I've got a round one somewhere. So that's just pretty much just raise temp till I hit that temp, after the mash in time is up. The figures I have to go on are these now...

34L strike water

5.5L loss from grain absorption

giving me a possible 28.5L pre-boil volume, maybe lose about 6.5L boiling,(60 min from hot break) and come up with 22L after boil. Still have to cool and transfer to fermenter. Have I got those figures wrong? This is with no sparge.

My Target OG is 1.052

My Target FG is 1.011

Target ABV is 5.4% 

[Steve Dorrington]

Darren,  my system is no sparge.  I start with 37L or 39L depending whether its a 60 min or 90 min boil.   That will get me 23 to 25 L into the fermenter depending on how hard the boil is.  If you're bottling it really doesn't matter how much you get as long as there's a bit of headroom in the fermenter.   Even with 23L kegs if there's more than 22L in the fermenter some goes into 500mL bottles before I put the rest into the keg.  (I've measured 4.5L /hr boil off, grain absoption I've found is about 1L/kg and a litre or so for shrinkage.) 

cheers steve

[Darren Andrews (Daza)]

Thanks Steve, do you do BIAB too? What size pot do you have? I will be doing s 60min boil start time from hot break, I'll try 34L with s slow rolling boil. I really need to watch where I set my adjuster on regulator do I'll know if I need to adjust that for next time.

[Steve Dorrington]

Darren, My main system is a no sparge 2 vessel system.  Insulated 38L chillybin and 65L pot.  I heat up my 37 or 39L to strike temp then pump 2.6L/kg of grain to the mash tun and mash in.  I start recirculation at 60 mins for approx 30 mins then turn the pump off and let everything drain to the kettle.  Preboil is around 31 to 33L.

My mini system is BIAB and uses a 26L pot on a 2 row gas burner.  I'm doing 8L batches (so about 1/3 a regular brew).  I start with 12L of water (50% more than the batch size) and to get a 67degC mash the strike water is ~70degC.  Just adjust it with a little boiling or cold water to get the temp you want.  Then close it up. 

I watch the boil and tweak the gas valve to the position needed to keep the rolling boil. It varies during the boil.   Start with the 34L and see what you get?   Next time adjust to get closer to your target but don't get hung up on it, it doesn't really matter.   Get a refractometer if you don't have one.  Then you can measure the SG at various points like pre boil and at the end of the boil.   

Good luck   

 

[Darren Andrews (Daza)]

So the recipe I am looking at doing now has a grain bill of 7.48kg for a 6 gallon batch(23 litre) so allow for grain absorption of 7.48litres of water? right? and 4.5 litres of water loss per hour of boil?

So maybe start with a strike water of 36Litres??

My OG target is 1.072 and FG is 1.017 with a ABV of 7.4%

[Adrian]

I also use the calculator (now called BIABaccus) at http://www.biabrewer.info/viewtopic.php?f=25&t=189 it's easy to tailor it to your system and I have found it to be really accurate with volumes, gravities etc. There is loads of great info on the website

[Darren Andrews (Daza)]

every-time I open that link it's a closed thread. I found this very helpful though

http://biabcalculator.com/

[Adrian]

Here's the excel spreadsheet that the link should take you to. To be honest the link that you've posted is much simpler and more than adequate by the looks of things