OG - SG calculation WHEN DILUTED

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hockayak

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Okay, i'm new here. I had a look around and couldn't find any info specifically about what i'm looking for. So here goes. I've been brewing a little while with successes ranging from not great (but drinkable) to pretty much craft beer results. I'm playing about a bit, with my very basic kit. I either use malt extract cans or fresh wort kits.

I made one of the All Inn Brewing Mutiny Red IPA - fresh wort kit brews, and it was excellent. A really good drop. Now, when brewing it a second time, i wasn't concentrating (quite literally) and where the 15L kit says you can top up to 20L - with water, i accidentally went to 25L. I.e. I now have 15L wort with an additional 10L of water. The OG is on the 15L cube. But can i truly use that OG, when i have then diluted it further. I have an SG at the end, but the OG wouldn't surely be at all accurate as i imagine that water is less dense than the wort cube, therefore stuffing up my alc calculation. Can you even do a calculation when the volume of the OG is 15L and the SG is at 25L? Does anyone know of a way to factor in additional tap water into the alc equation?

Could this quite literally work with ratios? i.e. 3/5s at the known OG of the kit, 2/5 at known SG of water and then average to get an overall OG for MY WORT?

Secondly, whilst i immediately buggered the quantities on this brew, i followed through and I have something which looks and smells pretty good. It'll be weaker alc wise, i'm okay with that, but is it possible, even after primary fermentation, to add something simple to add a bit more body, head, mouthfeel etc without just adding a complete second wort kit cube? For instance, could it be rescued with half a tin of a similar malt extract, just stirred in or is it more complicated than this? I'm guessing the alc is now what it is, and i can't likely change that in my big white bucket. But to add something more to get it somewhere enjoyable would be great. Any ideas?

Regards, Hockayak
 
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According to the dilution tool in beersmith and the OG on the cube of the Mutiny IPA I’ve got in the cupboard for emergencies the following should be true.

15L FWK @ 1.060 diluted to 25L should have a gravity of 1.036. If that ferments down to 1.010ish you’re still looking at a mid strength beer around 3.4-3.5%.

Can’t really help you with the improving mouthfeel etc however I strongly recommend getting yourself a hydrometer to check starting and finishing gravities, and to confirm when fermentation has finished.
 

MHB

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There is a very simple little equation called "The Standard Dilution Equation" as you can gather from the name diluting stuff is a pretty common job for brewers.
C1V1 = C2V2
Where
C is a C concentration
V is a Volume
The other thing you have to get your head around is that in a SG number the 1.000 part cant be used in an equation as it is non-unitary, it is just saying what the unit mass is compared to water i.e. 1L of 1.050 wort would weigh 1.050* 1L of water or 1.050g.
You can use oP (SG=(4*oP)/1000+1 , or you can rearrange that to (SG-1)*1000/4 = oP i.e. (1.050-1)*1000/4=12.5oP
You can work in Points 1.050 is called 50points.
You can just remove the ones 1.050-1 = 0.050.

Just to do it quick and dirty if you had 15L of 1.060 wort and you diluted it to 25, plug what you have into the equation
15L*60=25l*X, 15/60/25=36points or 1.036.

At the start you could have added some DME or LME to make up the gravity, wouldn't have fixed the bitterness, you could have done a small side boil in a pot to up the IBU's, even added some taste and aroma hops. after the ferment it is probably a bit late to try corrections.

You can get your Alcohol content in the normal way just use the 1.036 as your OG and what ever FG you got (say 1.008)
In points using the standard equation (Chang in gravity)/7.5.
36-8=28, 28/7.5=3.73333%.

You can trust the dilution equation and every brewer should know it, useful for diluting alcohol, bitterness, colour even water salts and cleaning chemicals.
Th SG to Plato (oP) isn't exact, it is however closer than you can measure with most hydrometers over the brewing range (say 1.000-1.100).

Mark
 

hockayak

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According to the dilution tool in beersmith and the OG on the cube of the Mutiny IPA I’ve got in the cupboard for emergencies the following should be true.

15L FWK @ 1.060 diluted to 25L should have a gravity of 1.036. If that ferments down to 1.010ish you’re still looking at a mid strength beer around 3.4-3.5%.

Can’t really help you with the improving mouthfeel etc however I strongly recommend getting yourself a hydrometer to check starting and finishing gravities, and to confirm when fermentation has finished.
Yeah i have a Hydrometer, thats how i worked out the SG of my final brew, but just wasn't aware of the calc to take into consideration the dilution factor. Yeah i get 3.42% or something similar. I wonder if it would be worth brewing a stronger, more concentrated batch of a malt can IPA and blending the two to up the alc and body of the brew. Thoughts?
 

hockayak

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There is a very simple little equation called "The Standard Dilution Equation" as you can gather from the name diluting stuff is a pretty common job for brewers.
C1V1 = C2V2
Where
C is a C concentration
V is a Volume
The other thing you have to get your head around is that in a SG number the 1.000 part cant be used in an equation as it is non-unitary, it is just saying what the unit mass is compared to water i.e. 1L of 1.050 wort would weigh 1.050* 1L of water or 1.050g.
You can use oP (SG=(4*oP)/1000+1 , or you can rearrange that to (SG-1)*1000/4 = oP i.e. (1.050-1)*1000/4=12.5oP
You can work in Points 1.050 is called 50points.
You can just remove the ones 1.050-1 = 0.050.

Just to do it quick and dirty if you had 15L of 1.060 wort and you diluted it to 25, plug what you have into the equation
15L*60=25l*X, 15/60/25=36points or 1.036.

At the start you could have added some DME or LME to make up the gravity, wouldn't have fixed the bitterness, you could have done a small side boil in a pot to up the IBU's, even added some taste and aroma hops. after the ferment it is probably a bit late to try corrections.

You can get your Alcohol content in the normal way just use the 1.036 as your OG and what ever FG you got (say 1.008)
In points using the standard equation (Chang in gravity)/7.5.
36-8=28, 28/7.5=3.73333%.

You can trust the dilution equation and every brewer should know it, useful for diluting alcohol, bitterness, colour even water salts and cleaning chemicals.
Th SG to Plato (oP) isn't exact, it is however closer than you can measure with most hydrometers over the brewing range (say 1.000-1.100).

Mark
This is great, thanks so much for the detailed explanation. Really appreciate it. Your thoughts re blending my mid strength with a higher ABV brew to balance out?
 

MHB

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Personally, I would taste it and see if you like it, brew another at full strength (OG~1.060), blend the two in a glass, your call have a big'n and a little'n or an inbetweener...
This is where we get away from right answers in Brewmaths and into personal taste, no right answer just personal taste.
Mark
 

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