reason for missed gravity

[bobeer]

Hey all. I brewed a rye IPA on national homebrew day and I missed my target gravity by 10 points. I wanted it to be about 1.062 but it ended up at 1.052. I made the recipe in beersmith and it looked fine on paper so I'm wondering why I missed the gravity.

Here's the breakdown... I used 11 lbs of 2row and 1 lb of rye malt. I used the equation of 12 lbs of grain X 1.25 quarts which = about 3.5 gallons of mash water.

I milled the grains myself, like usual, and the crush looked good to me. All the husks were cracked and it wasn't floury at all.

I boiled for 90 minutes and was left with just under 5 gallons of finished wort which is what I wanted to do-- a 5 gallon batch.

Is there a big of a difference in the thickness of the mash to the target gravity? Should I have used 1.50 quarts per lb of grain? I stirred the mash a few times throughout the 60 minute mash time.

The brew day went very well and the beer will still be a good brew but I'm sort of scratching my head as to why I missed the gravity. The only thing I can think of is either the mash thickness or the crush; even though both of those looked ok to me.

 

[eluterio]

10 points is a big difference, are you sure your hydrometer was calibrated? That's the first thing I look at before I start breaking it down.

Looking at your profile you have been on the site for a few years, so Im assuming you have made several all grain batches of beer.

If this is the case have you made multiple batches of beer without changing your brewing process and have hit your numbers, ie. grain mill, mash tun, sparging, and water ratio?

 

[bobeer]

Yea, I've been brewing since 2012 and doing all grain batches for 2 years or so. I haven't changed my equipment since I built my mash tun about 15 months ago or so. I've made some pretty great beers and I've nailed my OG most of the time; or usually get within a couple points.

I've been using the same hydrometer ever since I started brewing. It's off a tad but I make the needed adjustments when taking a reading.

As far as the mill goes I got it last August so I've done several batches with it too. I just crush the grain by line of site by what I know I was getting at my lhbs. I've gotten good readings in the past while using the mill so I don't think the crush is the culprit.

I'm sort of wondering about the thickness of the mash. I think i've read it can affect how fermentable the wort is but I'm wondering if it can affect the gravity of the beer.

 

[eluterio]

If you your process is the same as always, have you always mashed with grain to water ratio the same?

This one is a tough one and might require some long thinking. Mashing at 1.50 grain/water I don't think would have made a significant increase of 10 points IMO. I usually mash about 1.15 ratio and usually im on close to what I want. I don't think going all the way up to 2.0 will significantly increase your mash eff.

I would recalibrate your hydrometer just to make sure.

Another thing that could have been the culprit, mash ph. Maybe for some reason the grains you had didn't get you what you wanted on your ph scale to effectively brake down enzymes.

Maybe your sparging method was to fast and you didn't get all the sugars out of the mash. Do you know what your mash gravity was when you reached your full volume?

 

[peterj]

Have you ever brewed with rye malt before? Rye doesn't have a husk like barley and it's a little smaller. I believe if you don't tighten your gap for it you won't crush it very well. I don't know if that would account for being 10 points off though.

 

[eluterio]

Have you ever brewed with rye malt before? Rye doesn't have a husk like barley and it's a little smaller. I believe if you don't tighten your gap for it you won't crush it very well. I don't know if that would account for being 10 points off though.

on just 1 lbs of rye?

 

[Paradigm]

Well we can all agree that it's an efficiency question. Could it just have been old grain? Maybe it got wet in the past? That's really the only thing I can think of (besides a faulty hydrometer) if you did the same thing as usual.

 

[peterj]

on just 1 lbs of rye?

Right, that's why I was saying I don't think it would account for being 10 points off. But assuming the worst (that the rye malt didn't get crushed at all and didn't give you anything), you would have about a 5 or 6 point drop in gravity in a 5 gallon batch. It could be that combined with some of the other factors mentioned. Or that would bring it close to the range of a normal fluctuation.

 

[LandoLincoln]

What was the pre-boil SG?

 

[eluterio]

Right, that's why I was saying I don't think it would account for being 10 points off. But assuming the worst (that the rye malt didn't get crushed at all and didn't give you anything), you would have about a 5 or 6 point drop in gravity in a 5 gallon batch. It could be that combined with some of the other factors mentioned. Or that would bring it close to the range of a normal fluctuation.

Hmmm ok I can see that. Theres so much that it could be and really tough to narrow it down. Just tons of Idea's of what it could be.

Besides missing the OG it still will make beer, HAHA.

 

[bobeer]

Thanks for all the replies, folks.

I did close the gap on the mill a tad before crushing the rye. I guess that could be another culprit. How crushed is the rye supposed to be? In my test crush they were all cut in half or a little more.

The grain I assume is fresh. The lhbs I go to has a pretty fast turn around. Grain doesn't sit in the shop.

I'll test my hydrometer and see if it's changed for some reason.

I didn't take a gravity reading after the sparge. I was doing a few other things while my buddy and I were hanging out.

I've been meaning to get into the ph stuff but I just haven't had a chance to look into what grains do what to the ph and what additives I can use to adjust the ph reading. I know some about it but not enough to actually try messing with it.

 

[eluterio]

Well good luck all the things we mentioned have been reasons. If your next batch comes out low as well it might be time to take better notes through out the entire process again. Been there done that!!

 

[bbohanon]

I would agree with the others here that it could be alot of different things and could be difficult to nail doan.

If you have your efficiency dialed in from previous batches (I.E. - You are consistently hitting your numbers based on your recipes, crush settings and efficiency numbers previously until you did this particular batch), then its something else..maybe the grain was old or it is time to start dialing in your mash PH to maximize conversion. I know once I started be a good steward of my water PH, its very rare I do not hit or exceed my SG.
Different styles of beer require different water treatments to get that batches PH dialed in and trust me, PH does matter if optimal conversion of your grains are your goal(and it should be).

The other simple option if you dont want to deal with stuff like water PH is to just add more fermentables to the grain bill for this particular recipe next time to pull your target 10 points above your intended target to see if you actually hit the target next time. Alot of folks will do this rather than dial in where the efficiency loss truly occured.

 

[bobeer]

Thanks guys.

I think I'm going to close the crush a tad more and get some ph strips to see where I'm at. I need to make some time to figure out how deal with the ph and how to adjust it on the fly. My beer has always been good but I'm ready to take it to the next level and make it great.

 

[Themisfitking]

I check my mill with feelers before every batch, I found the rollers out of adjustment before

 

[jonpecan]

I recently had my first big OG miss as well after several years of all grain brewing. I believe the culprit in mine was low mash temp, I got a little complacent in my temp readings (and thinking mid 140s would be "good enough" for my particular grain bill, so long as I mashed for long enough), trying to brew several brews back to back.

Since I didn't see it mentioned by anybody else, thought I'd toss mash temp out there!

 

[TheHappyHopper]

My money is on a low mash pH - I had a couple batches when I first started getting into water chemistry that ended up with an efficiency around 60% (where I was frequently in the mid 70s) after I started adding acid malt - once I got a pH meter, I found that I didn't need the acid malt as it was causing my low pH. Once I stopped using it, my efficiency numbers are back up.

 

[bobeer]

I recently had my first big OG miss as well after several years of all grain brewing. I believe the culprit in mine was low mash temp, I got a little complacent in my temp readings (and thinking mid 140s would be "good enough" for my particular grain bill, so long as I mashed for long enough), trying to brew several brews back to back.

Since I didn't see it mentioned by anybody else, thought I'd toss mash temp out there!

I hear you. I did do a low mash at 148 so maybe that was it. Maybe I'll brew the beer again but with a little more malt to see if that helps. Thanks!

 

[peterj]

My money is on a low mash pH - I had a couple batches when I first started getting into water chemistry that ended up with an efficiency around 60% (where I was frequently in the mid 70s) after I started adding acid malt - once I got a pH meter, I found that I didn't need the acid malt as it was causing my low pH. Once I stopped using it, my efficiency numbers are back up.

With a pale IPA grain bill and no water additions (salts or acids) I doubt his pH was too low. If anything it would have been high. But since this is the only time he's missed his OG by this much (I'm assuming he's brewed beers with similar grain bills before), water chemistry and pH wouldn't be my first guess.

 

[bobeer]

OK... I think I found the culprit. I noticed when I was milling some 2row that whole kernels were somehow making it into the bucket of crushed grain. There was a gap between the hopper and the mill rollers juuuuuuust big enough to let grain slip through. I'm really not sure how that happen but it probably happened by carrying it by the hopper. A few screw adjustments and we're all good again. Came within 2 points of my target gravity after the adjustment. I probably would have nailed the OG if I noticed it right away.

Mystery solved. :rockin:

 

[peterj]

OK... I think I found the culprit. I noticed when I was milling some 2row that whole kernels were somehow making it into the bucket of crushed grain. There was a gap between the hopper and the mill rollers juuuuuuust big enough to let grain slip through. I'm really not sure how that happen but it probably happened by carrying it by the hopper. A few screw adjustments and we're all good again. Came within 2 points of my target gravity after the adjustment. I probably would have nailed the OG if I noticed it right away.

Mystery solved. :rockin:

Nice, I'm glad you got it figured out! And I'm glad it was something that was really simple to fix. Thanks for posting an update. Now BREW ON!!