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General Category => All Grain Brewing => Topic started by: gmac on May 01, 2011, 03:32:05 PM

Title: Water volumes for low gravity beers
Post by: gmac on May 01, 2011, 03:32:05 PM
I'm wondering how I would manage the water volumes for a lower gravity brew?
Right now, I'm putting 22-23L of water into my tun which equates to about 2L/lb because I'm usually at about 10 lbs total grist.  From this I normally get about 14L of wort at around 1.070-1.072.  I then add 16 to 18L of hot water, batch sparge and get about 16L of second runnings for a total of 30L which works out very well for my 23L fermenters.  I don't take the gravity of the second runnings but I do take the gravity of the final pre-boil volume which has been about 1.044 or so the last couple times.  

But, I want to reduce the gravity of my beer down to 1.040 OG, post boil.  I will reduce my grain bill accordingly but what do I do with the water volumes?  If I stay at 2L/lb, I'll only put in about 12L at the start and I expect I'll only get about 8L back from that.  Do I then put 22 more in the tun for the sparge or should I stick with the 22/16 ratio?  I know less grain will hold less water so I may not get as much absorption so 20/14 may give me what I need but I'll still have over 3L/lb in the mash tun.  Is this a problem?  I see most people are somewhere around 1-1.5L/lb, I started there but got better efficiency at 2L/lb.  



Title: Re: Water volumes for low gravity beers
Post by: malzig on May 01, 2011, 04:59:51 PM
What gravity are you shooting for?
Do you really have a 3L dead space?
Are you really boiling off 2.5 gallons?

Since you seem to be getting around 85% efficiency, if you want to make 5 gallons of a 1.048 beer you'll start with 8# of grain.

8# of grain will absorb just about 1 gallon, so you'll need 5 gallons + 1 gallon + dead space + boil-off. 
From what you've said, you need 5 + 1 + 0.75 + 2.5 = 9.25 gallons to go through your tun.

5 gallons into the mash and 4.25 gallons into the sparge should get that done.  That's 2.5 qt/# mash thickness, which you can split into 4 gallons and a 1 gallon mashout, if you want to keep your 2 qt/# thickness.  2.5 qt/# will work fine, though.
Title: Re: Water volumes for low gravity beers
Post by: gmac on May 01, 2011, 06:01:42 PM
What gravity are you shooting for?  

1.040
Do you really have a 3L dead space?

No, almost no dead space but I know I put in 22L, get out 14L.  I'm measuring the volume going in and out.  If I let it sit for 1/2 an hour or more, I will get maybe an extra liter but it runs very, very slowly, practically a trickle.

Are you really boiling off 2.5 gallons?

I'm boiling off about 6 liters - sometimes have a liter left in the bottom of the pot with the hop sludge since I accidentally flushed my hop bag (long story).  I may be  boiling too aggressively but it's been working so I've left things about the same.

I was thinking of about 5.5 lbs of pale malt, 1/2 lb C45, 1/2 lb instant oats for more body, 50 grams of chocolate malt, mostly for colour. 6.5 lbs of fermentables.  Yeast will be London III used for the 3rd and last time.  1/2 oz of Northern Brewer at 60, 1/2 oz of East Kent Goldings at 15, 1/2 oz of EKG at flameout.
Title: Re: Water volumes for low gravity beers
Post by: weazletoe on May 01, 2011, 08:32:00 PM
Google Mashwater 3.3, download it, and all your problwems will be over.
Title: Re: Water volumes for low gravity beers
Post by: gmac on May 01, 2011, 10:58:48 PM
Google Mashwater 3.3, download it, and all your problwems will be over.

I thought bacon was the answer to all life's problems? 
I googled it and found what I thought was a link but no luck. 
Also, I am doubtful it'll work on a Mac. 
Thanks for the suggestion, I'll try again.
Title: Re: Water volumes for low gravity beers
Post by: Will's Swill on May 02, 2011, 12:46:56 AM
You could always make a smaller batch, say 4 gallons, and then dilute to your target O.G.
Title: Re: Water volumes for low gravity beers
Post by: weazletoe on May 02, 2011, 04:22:42 AM
Google Mashwater 3.3, download it, and all your problwems will be over.

I thought bacon was the answer to all life's problems? 
I googled it and found what I thought was a link but no luck. 
Also, I am doubtful it'll work on a Mac. 
Thanks for the suggestion, I'll try again.

If you want, let me know how much grist you're using, the size batch you're making, and your boil off, and I'll run it for you. Also, what mash ratio you want to use, and what your mash temp is.
Title: Re: Water volumes for low gravity beers
Post by: malzig on May 02, 2011, 10:31:59 AM
I was thinking of about 5.5 lbs of pale malt, 1/2 lb C45, 1/2 lb instant oats for more body, 50 grams of chocolate malt, mostly for colour. 6.5 lbs of fermentables.
So, a ~1.036 beer?

The math is veryu simple, it doesn't require a computer program:
6.5#t would be 0.8 gallons absorbed, so, 5 + 0.8 + 0.75 + 2.5 = 9.05 gallons

5 gallons in the mash and 4 gallons in the sparge would be close enough.  You could mash  at the resulting 3 qt/gallons, or mash in with around 3.5 gallons to get your usual 2 qt/# the add 1.5 gallons as a "mashout", just before you take the first runnings.

When I make small beers like this I don't sparge at all.  I put half the water in for the mash, then add the remaining half just before taking the runnings all at once.  That's what I'd recommend.  Your efficiency will drop to ~70-75%, so yo would need to increase the grain bill to about 7.5#.
Title: Re: Water volumes for low gravity beers
Post by: SpanishCastleAle on May 02, 2011, 11:39:10 AM
When I make small beers like this I don't sparge at all.  I put half the water in for the mash, then add the remaining half just before taking the runnings all at once.  That's what I'd recommend.  Your efficiency will drop to ~70-75%, so yo would need to increase the grain bill to about 7.5#.
This is pretty much what I do too.  Just rebrewed my NHC Mild (um...'export' Mild...yeah that's it ;)) on Saturday: 8# grain, doughed-in to 16 qt water and then infused with 10 qt water to mash-out, then sparged with a whopping 4 qt.  Got ~73% brewhouse efficiency.
Title: Re: Water volumes for low gravity beers
Post by: gmac on May 02, 2011, 02:46:25 PM
Thanks.  I'll add another lb of pale malt and give it a try.

Sounds like some sugar is left in the grain, I may try to do a few extra liters to get some of the sugars and freeze it or use it right away for a starter.
Title: Re: Water volumes for low gravity beers
Post by: malzig on May 03, 2011, 12:48:41 AM
Sounds like some sugar is left in the grain, I may try to do a few extra liters to get some of the sugars and freeze it... for a starter.
That's what I do.
Title: Re: Water volumes for low gravity beers
Post by: gmac on May 03, 2011, 01:19:24 AM
Well, I really screwed this one up.  Put in 20L at the start with 6 lbs pale malt, 1/2 lb C45 and 1/2 lb 1-minute Oats (man I hope I didn't have to cook those).

Sparged with "some water" but didn't measure this time which I should have and I've always done before.  Ended up with about 30L of wort.  I also dialed back my boil intensity based on some previous questions.  I think I only boiled off about 5L because I ended up with 25L of 1.034 wort (anyone wanna guess at the % efficiency?  I have no idea what to do with oatmeal).  I should have taken a gravity before flameout but I was eyeballing it.  Was shooting for 1.040, ended up at 1.034 so this will be nice and mild.  Probably over hopped too (3/4 oz NB at 60, 3/4 oz EKG at 15, 1 oz of Willamette at flameout) but oh well, this is the first go.

Did get 6 L of starter for the next time.
Title: Re: Water volumes for low gravity beers
Post by: Hokerer on May 03, 2011, 03:30:51 PM
1/2 lb 1-minute Oats (man I hope I didn't have to cook those).

You're fine.  The 1-minute (and for that matter, the 5-minute and instant) oats have all already be gelatinized so you can just put them straight into the mash.
Title: Re: Water volumes for low gravity beers
Post by: morticaixavier on May 03, 2011, 03:40:19 PM
1/2 lb 1-minute Oats (man I hope I didn't have to cook those).

You're fine.  The 1-minute (and for that matter, the 5-minute and instant) oats have all already be gelatinized so you can just put them straight into the mash.

in fact all rolled oats are pre gelatenized. The process of making rolled oats is to steam them and then squash them while still hot and soft.
Title: Re: Water volumes for low gravity beers
Post by: Hokerer on May 03, 2011, 04:06:39 PM
because I ended up with 25L of 1.034 wort (anyone wanna guess at the % efficiency?  I have no idea what to do with oatmeal).  I

I've heard 31 ppg for oats (versus 36 for barley malt).  Using that number would mean that your grist would provide (6 * 36) + (1/2 * 36) + (1/2 * 31) = 249.5 gravity points.  That many points in the 25L (6.6 gallons) you ended up with would give you a gravity of 249.5 / 6.6 = 37.8 or ~1.038.  Since you ended up with 1.034, your efficiency was 34 / 38 = 89%.  That's pretty darned high.
Title: Re: Water volumes for low gravity beers
Post by: Hokerer on May 03, 2011, 04:07:59 PM
You're fine.  The 1-minute (and for that matter, the 5-minute and instant) oats have all already be gelatinized so you can just put them straight into the mash.

in fact all rolled oats are pre gelatenized. The process of making rolled oats is to steam them and then squash them while still hot and soft.

It's the "steel cut" type oats that do need to be cooked, right?
Title: Re: Water volumes for low gravity beers
Post by: gmac on May 03, 2011, 04:13:41 PM
Thanks Joe.
I should have mentioned that this had an almost 2 hour mash.  I had a dentist appointment so I put this on before I left and was longer than I anticipated.  If it's any good I may name it Root Canal Mild...
Title: Re: Water volumes for low gravity beers
Post by: Will's Swill on May 04, 2011, 04:32:59 AM


It's the "steel cut" type oats that do need to be cooked, right?

Yep, that's right.