If I sparge with water will it add to the gravity or dilute

[mtnagel]

So let's say after pulling the bag, draining and squeezing the bag as much as I can, my pre-boil gravity and volume are both low. If I were to sparge with water through the bag, will it increase, decrease or not change the gravity?

My gut says it will decrease it some because you probably aren't getting much more sugars out, but it's not the same as diluting with water. Correct?

 

[Sippin37]

You will probably dilute but there will still be some sugar coming out with the sparge water. Definitely better than just diluting with water. Your best bet if you want to hit your target gravity is to lower your batch size. Or you can add some DME to bring it up to your target OG.

 

[mtnagel]

Thanks. Just wanted to confirm my thinking was right. My batch yesterday was low by only 3 or 4 points, so I didn't do anything. I'm okay with small differences in gravity or volume.

 

[Setesh]

It will definitely lower the gravity of the wort. Since the grains have given up most of their sugars the water you put over them (sparge water) will rinse the grains removing some more sugar but won't be nearly as high in sugar as the first runnings (what is already in your pot). As mentioned above, this is much better than just adding plain water. If you are still low just add some DME as suggested above. It won't hurt a thing. I always keep a bag of DME around for this very reason. If I'm low I will add DME, if I'm high I'll dilute with water before the boil or adjust the recipe in BeerSmith before the boil. Otherwise your hop extraction will be off since your gravity wasn't correct as per the recipe.

 

[Setesh]

Thanks. Just wanted to confirm my thinking was right. My batch yesterday was low by only 3 or 4 points, so I didn't do anything. I'm okay with small differences in gravity or volume.

Oh yeah, 3-4 points you are golden.

 

[mtnagel]

Actually, just looked it up, I was only 2 points off yesterday, so I didn't feel a correction was necessary. I've been up to 5 points off and haven't corrected. How much would that mess up the hop extraction?

 

[Setesh]

Actually, just looked it up, I was only 2 points off yesterday, so I didn't feel a correction was necessary. I've been up to 5 points off and haven't corrected. How much would that mess up the hop extraction?

According to BeerSmith an difference between 1.056 and 1.051 increased the IBU from 34.4 to 35.8. That is a tiny difference, I don't think you would have a prayer of noticing that unless you did a side by side.

 

[CountryGravy]

For me, saying it "dilutes the wort" misses the point.

Let's say I'm looking for 5 gallons @ 1.060 as my pre-boil gravity. If I mash with the entire 5 gallons and come up short at 1.055, I've missed the mark and I'm leaving a lot of sugars in the mash.

However, if I mash with 4 gallons and get 1.068 for those 4 gallons, and then sparge with one gallon and get 1.030, I've used that extra gallon to wash out the extra sugars and I'm at my mark.

So, you've diluted the 4 gallons down from 1.068, but you've collected the extra starches and hit your mark by sparging with the other gallon.

Does that make sense?

4 gallons @ 1.068 = 4 x 68 = 272 points
1 gallon @ 1.030 = 1 x 30 = 30 points
272 + 30 = 302
302 points/ 5 gallson = 60.4 points, or 1.0604 SG

 

[mtnagel]

Let's say I'm looking for 5 gallons @ 1.060 as my pre-boil gravity. If I mash with the entire 5 gallons and come up short at 1.055, I've missed the mark and I'm leaving a lot of sugars in the mash.

Or couldn't it be that I overestimated my efficiency? And no amount of sparging will get me my gravity?

 

[fearwig]

More sparging will pretty much always get you your gravity if you're willing and able to boil off the extra water. Of course at a certain point that becomes impractical and you start extracting tannins (under 1.010 is a rule of thumb but it depends on pH). It takes a good bit of sparging to get to that point. No-sparge BIAB leaves a lot of sugar in the spent grains.

Efficiency varies depending on grain bill and lautering and everything else, it's too often thought of as an independent variable when you really ought to be tweaking it in your head based on the size of your mash.

I have come in significantly under gravity before and I decided to sparge another gallon and a half (it was coming in around 1.025 still) and put it in a separate pot to boil it down while my main boil was running. Came out great.