Different efficiencies?

[mbbransc]

Saturday, I brewed two IPAs, both using 13# of 2-Row and 1# of sugar. I calculated my recipes based on 75% efficiency (I'm still dialing in my equipment and processes) with one batch being 5gal into fermenter and the other 5.5gal. My expected OG was 1.084 and 1.075 respectively. What I got was 1.075 on IPA #1 (expected 1.084) and 1.088 on IPA #1 (expected 1.075). What could account for such a drastic difference in efficiency (72% versus 86%)?

Here are the steps I took to IPA #1:
- mashed 4.25gal at 149* for 75min
- batch sparged 3.75gal at 170* for 15min
- I didn't lose as much water to grain as I thought so I boiled this batch 15 minutes before starting my 90min additions and continuing on.
- Ended up with 5.5 gal at 1.075. Not terribly off my calculations since I ended up with 0.5gal too much wort.


Here are the steps I took to IPA #2:
- mashed 4.25gal at 150* for 90min (mashed longer because timing problems overlapping my two brews)
- batch sparged 2.75gal at 170* for 15min (decreased volume based on experience with IPA #1)
- 90min boil as planned and ended up with 5gal at 1.088.


So, best I can tell, IPA #1 ended up being what I calculated as IPA #2 in terms of volume and OG. And IPA #2 ended up being slightly higher than what I'd calculated for IPA #1.

But what it comes down to is I barely missed my efficiency in IPA #1 and really overshot it in IPA #2. From the differences I've outlined here, does anything stand out to attribute to a difference in efficiency of 86% versus 72%?

 

[KeyWestBrewing]

If you hadn't gotten the extra 1/2 gal of wort on the first IPA you would have had a gravity of exactly 1.084. Hitting your target volume and 75% efficiency. So you just collected too much runnings into the BK. The longer mash in the second IPA could have helped you get better conversion and higher mash efficiency. Did you possibly sparge faster with batch 1 than you did batch 2?

 

[Hello]

^ I think he had to of batch sparged quicker with batch 1 if he batch sparged more water on #1 but says 15 minutes for both. What you did point out is if he stopped his runnings 1/2 gallon sooner he would have hit his target. Is there where taking a reading using a refractometer would come in handy? I never even thought about that.

 

[KeyWestBrewing]

^ I think he had to of batch sparged quicker with batch 1 if he batch sparged more water on #1 but says 15 minutes for both. What you did point out is if he stopped his runnings 1/2 gallon sooner he would have hit his target. Is there where taking a reading using a refractometer would come in handy? I never even thought about that.

Good point. In my experience and from what Ive read sparging slower will help you rinse more from the mash. And for batch one you had to have collected too much to end up with too much meaning you overshot your pre boil volume. Measuring the runnings will only tell you what your pulling. Sometimes but not always an indicator of when you need to stop though since the gravity of the runnings gradually decreases. You need to know when your at your target pre boil volume otherwise your starting to dilute the wort you've collected with low gravity runnings.

If your at the right pre boil volume and your gravity is low then your having problems somewhere between the mill and your BK. Either poor crush, conversion, or an inefficient sparge. So you need to know your volume and gravity not just one of the two.

 

[mbbransc]

I had a refractometer on hand but didn't measure until after I dumped my sparge wort into the BK (that's when I took all my measurements and realized I needed to boil off some water before beginning my real boil). So it sounds like I should have been better monitoring my volume in the BK.

I made a volume adjustments to the second batch but still came in way over on my gravity. Is it due to just the estimated additional 15min in the mash and 0.5 gallon less volume than I calculated the recipe for? I calculated the total gravity points and I was about 27.5 over. Adjusting for volume, I would have still come in about 0.005 points high in my volume was correct. I guess saying it that way doesn't sound like as much of an error.

OK, let me ask this... if it too late to dilute batch two? I pitched SAT afternoon.

I also think my yeast starter may have been too small now. Looking at MrMalty, it says I needed a 3L starter. I only needed a 2L for the original recipe.

Oh how the errors keep snowballing...

 

[KeyWestBrewing]

I had a refractometer on hand but didn't measure until after I dumped my sparge wort into the BK (that's when I took all my measurements and realized I needed to boil off some water before beginning my real boil). So it sounds like I should have been better monitoring my volume in the BK.

I made a volume adjustments to the second batch but still came in way over on my gravity. Is it due to just the estimated additional 15min in the mash and 0.5 gallon less volume than I calculated the recipe for? I calculated the total gravity points and I was about 27.5 over. Adjusting for volume, I would have still come in about 0.005 points high in my volume was correct. I guess saying it that way doesn't sound like as much of an error.

OK, let me ask this... if it too late to dilute batch two? I pitched SAT afternoon.

I also think my yeast starter may have been too small now. Looking at MrMalty, it says I needed a 3L starter. I only needed a 2L for the original recipe.

Oh how the errors keep snowballing...

You'll need to monitor your volume and the gravity. The volume being the reason you missed your mark in batch one. I think the slower sparge(relative to the sparge volume vs time) is probably what boosted your efficiency in batch 2. Not a bad thing if your hitting the right pre boil volume.
At this point I wouldn't worry about adding water. You got the batch size you wanted with higher efficiency than expected. Keep brewing to get dialed in with your system. Make sure your hitting the right volumes and being consistent for each step on brewday and soon enough you'll be getting more consistent efficiency. RDWHAHB

 

[KeyWestBrewing]

Here's a good thread on how to mark your BK. Definitely makes things easier....

https://www.homebrewtalk.com/f51/how-add-permanent-volume-markings-kettle-illustrated-463099/