Really Bummed - Missed OG by 18 points - Advice for Beginner Batch Sparger

[MEPNew2Brew]

So, I brewed my first 5 gallon AG batch with a mash tun - cooler with stainless steel mesh tube. Denny's Wry Smile IPA AG kit from Northern Brewer. Hit my temperatures (151 mash; heated sparge water to have grain bed hit about 168). Mashed 75 minutes.

Stirred in the sparge water quite a bit.

Sparge seemed a bit slow and had to add an additional gallon of sparge water to get pre-boil volume.

Still, 18 points off, even after adding a 1/2 lb extra 2-row.

Where do beginners usually go wrong with batch sparging?

Recently tested hydrometer.

Any thoughts on what to focus on next time around would be appreciated.

Can't believe I missed by 18 points.

 

[Shakybones]

What was the crush like on the grain? Poorly crushed grain (as I've seen from the online HBS's) = low efficiency = low OG.

Did you leave a lot of liquid in the cooler but still hit your desired batch volume? Extra sparge H2O + poor drainage/stuck sparge = low efficiency = low OG.

What was the temp of your hydrometer sample?

 

[kh54s10]

Most often this type of problem is due to a coarse crush on the grains. I haven't heard or experienced this with NB, I did a couple of their AG kits.

18 seems huge. Maybe take another reading to check?

Another thing to check is that your thermometer is accurate. 32 degrees in crushed ice with just enough water to fill. And 212 degrees at boiling at seal level. Lower at elevation.

 

[MEPNew2Brew]

One other piece of potentially relevant information - final runnings from the sparge came in at 1.029.

Seems like I left a whole lot of sugar behind. What should the final runnings be?

 

[kh54s10]

One other piece of potentially relevant information - final runnings from the sparge came in at 1.029.

Seems like I left a whole lot of sugar behind. What should the final runnings be?

Single sparge or double sparge?

Was that the runnings from the sparge, or the preboil gravity? If preboil it is very low.

 

[Yooper]

One other piece of potentially relevant information - final runnings from the sparge came in at 1.029.

Seems like I left a whole lot of sugar behind. What should the final runnings be?

When you stirred in your sparge water, did you stir like it owes you money? That's really important- it's the stirring the "knocks" the sugars off of the grain and into the liquid.

Stir in the sparge water, stir thoroughly, then stir one more time, and then vorlauf and drain. It takes less than 5 minutes!

 

[MEPNew2Brew]

Thanks for all the replies.

Shakybones - crush looked pretty good. But, I have only a few AG batches under my belt. All the others have been BIAG. Sparge did seem to get "stuck". But, I stirred it again and it seemed to drain off pretty well. Hydro readings - takes a few times at various temps and corrected to the proper temp in any event.

KH54 - I have not checked my thermometer. I will do so. But, it is a less than year old Termapen.

Yooper - I don't think I stirred it enough. At the time, I thought I did. But, that seems to be the most likely culprit.

Thanks again all.

 

[MEPNew2Brew]

When you stirred in your sparge water, did you stir like it owes you money? That's really important- it's the stirring the "knocks" the sugars off of the grain and into the liquid.

Stir in the sparge water, stir thoroughly, then stir one more time, and then vorlauf and drain. It takes less than 5 minutes!

The 1.029 was after I had drained off enough to get my boil volume. After the second batch sparge, I had not hit my pre-boil volume. So, I ended another gallon of 185 degree-ish water and sparged about 2.5 quarts out. The 1.029 is some of what was left in the tun. Gain was still VERY wet after the sparge.

What should the final runnings be when you batch sparge? 1.029 seems high to me.

 

[Malric]

Did you see significant channeling? I had a batch that I thought I missed the OG by nearly 20 points. Turns out that the runnings had not mixed during run off. After I stirred the boil kettle, I was low by .03 instead of .19

 

[jdauria]

Don't have a solution for why you missed your gravity, but do have a fix to help you get back up to the right gravity after the fact.

Take your targeted pre-boil gravity and multiply by target pre-boil volume to get the gravity points you should have. Then take your Actual pre-boil gravity and multiply by your actual volume. Take the difference and divide by 45 and it will give you a total of how much DME to add to get to the target gravity.

For example, say targeted was 1.068 and TV was 6.5 gallons. 68x6.5 = 442 GU (gravity units). Your actual was 18 pts so using this example, then you hit 1.050 and 6.5g, so 50x6.5 = 325 GU. 442-325 = 117 GU missing. 117/45 = 2.6 lbs of DME to add to hit the recipe's pre-boil gravity.

 

[jdauria]

Wait, when you talk about missing the gravity by 18 points compared to the recipe, when did you take your reading? Are you comparing a reading after you sparged and before you boiled with the recipe's listed OG of 1.078? You WOULD BE very off if that is what you did because the recipe OG is AFTER the boil.

Using BeerSmith, it tells me based on my equipment the PREBOIL Gravity should be an estimated 1.068 which is 10 points lower then the recipe's OG, so you being off 18 if you were doing what I think you may have done would make sense somewhat.

 

[Bobby_M]

You never mentioned if you drained off the mash wort prior to adding any sparge water. Once you drain off your first wort completely, you measure that volume and determine how much you need to sparge with to get your total desired volume. If you want to start boiling with 6.5 gallons, which is pretty typical and you drain off 2 gallons of first wort, that means you need to sparge with 4.5 gallons. Once you get used to your system, you won't need to figure it out on the fly anymore, but it's foolproof for beginners.

 

[RacingRam]

I can't speak to your methods, but I just brewed the extract kit for this beer and the gravity came in very low - 1.065 instead of 1.078. I've never brewed an extract batch that was off by more than 5 points, so I don't think I did anything wrong, but I did have to brew inside this time and scorched some wort to the bottom of the kettle...hard to believe that cost me 13 points though. Maybe NB's calculations are off for this kit? I didn't double check the expected gravity based on what they sent me.

 

[jdauria]

I can't speak to your methods, but I just brewed the extract kit for this beer and the gravity came in very low - 1.065 instead of 1.078. I've never brewed an extract batch that was off by more than 5 points, so I don't think I did anything wrong, but I did have to brew inside this time and scorched some wort to the bottom of the kettle...

I notice when I brew inside, I don't get the same rolling boil like I do when using a propane burner outside. A less vigorous boil means less boil off, which means less condensing of the wort. Could explain not hitting the targeting number.

 

[RacingRam]

I notice when I brew inside, I don't get the same rolling boil like I do when using a propane burner outside. A less vigorous boil means less boil off, which means less condensing of the wort. Could explain not hitting the targeting number.

Very good point, I didn't even think about that! It was barely boiling, even with the eye turned up all the way. That surely was a contributor. No more using the big (15 gal) kettle on the stovetop!