Unusually low efficiency? What gives?

[scone]

I was hoping someone could help me diagnose my unusually low efficiency. Since switching to all-grain and doing proper mash-outs (I double batch sparge, heating to mashout before first run off seems to help me with efficiency), I've been seeing 80-81% total efficiency (including boil) for the last 5 or 6 batches of beer I've made.

This last batch ended up at 70%, which is a huge jump. My process was exactly the same as it always is with three exceptions:

(1) I tried no-chill this time, but can't have anything to do with it, right?
(2) I did a single decoction to hit mash out (5 quarts, boiled for 30 min.), pulled after 1 hour in the mash
(3) I treated my water with a little bit of phosphoric acid (20 mL of 10% phosphoric acid for 8 gallons of water)

It's really bizarre to me, given that I would think the decoction would *increase* my extraction potential... Could slightly more acidic mash water have something to do with it? I think we're talking like a .1 or .2 pH difference here...

Here's an overview of my process
* mash at 154F with 1.25 qt./lb.
* 1 hour mash
* after 1 hr, pulled 5 qt. decoction, boiled for 30 min. added back in before first run off
* double batch sparge with 168F water
* 1 hour boil

total water usage was 8 gallons 2.2 quarts for the whole shebang. Should have yielded 6 gallons of finished wort (unfortunately i have no way of verifying that it's exactly 6 gallons since I siphoned it into a pony keg) but it's definitely close to 6 gallons in any case, I would think a bit less if anything since the decoction boiled off some as well.

The only other thing I can think of is this. Most everything I brew has some crystal-type grains in it, and some amount of specialty grains, but this recipe doesn't. It's only 4 lbs. 2-row, 4 lbs. vienna, 4 lbs. munich. Could brewing without specialty grains cause a perceived drop in efficiency? (E.g. is my idea of my own brewhouse efficiency artificially inflated due to using "steeping-type" grains?)

 

[billl]

Unless you had a good reason to add acid, that could drop your efficiency. eg if you were at a mash ph of 5.2 and dropped to 5.0. You could easily drop a couple points there.

Also, while your mash out may have been at the same temp, you would have had less water than usual. Less water in the first runnings could definitely knock a couple points of too.

 

[scone]

My reasoning for the phosphoric acid was based on this: https://www.homebrewtalk.com/f39/austin-texas-tap-water-profile-80016/. zgardener mentioned it as a way that Austin pro brewer's treat the city water here (which I also use for my beer).

If it was just a couple of points I would chalk it up to a slight miscalculation of water or not stirring the mash enough or something, but it was 8 points, which seems like a lot to be off by when my other recent brews were dead on.

 

[billl]

Well, unless you changed more than those 2 variables, that is the only place to look. Taking a gallon of mashout water away certainly can change things.

Are you milling your own grain, of could that be another variable?

 

[scone]

Are you milling your own grain, of could that be another variable?

Nope. I always get Austin Homebrew to mill it for me.

 

[amandabab]

I'm going to say the acid too.

It's really bizarre to me, given that I would think the decoction would *increase* my extraction potential...

The decoction is the exact opposite way that I do it. After an hour your mash extraction should have been done completely anyways.

 

[helibrewer]

Do you know what your conversion efficiency was (expected extraction in the tun vs. the Gravity you measured in the tun)? I use 20% Phosphoric in my RO water and only need 0.1-0.2ml's to bring my pH into the 6's. I think 20ml's was a lot, did you measure the pH after the addition?

 

[scone]

Do you know what your conversion efficiency was (expected extraction in the tun vs. the Gravity you measured in the tun)? I use 20% Phosphoric in my RO water and only need 0.1-0.2ml's to bring my pH into the 6's. I think 20ml's was a lot, did you measure the pH after the addition?

Unfortunately I didn't measure the gravity until after the boil. I don't have a pH meter so I didn't measure that either (I've read that the strips are notoriously inaccurate so I didn't even go that route). My acid treatment amount was taken directly from that thread I referenced earlier. I'll definitely half it next time and see if that changes anything.

I wanted to try lowering the pH of my water just a tad since there is a hard to pinpoint astringent-y type flavor to all of my beers, and I thought it might have something to do with too high pH during sparging. It's pretty subtle, but it seems to always be there.

 

[helibrewer]

Unfortunately I didn't measure the gravity until after the boil. I don't have a pH meter so I didn't measure that either (I've read that the strips are notoriously inaccurate so I didn't even go that route). My acid treatment amount was taken directly from that thread I referenced earlier. I'll definitely half it next time and see if that changes anything.

I wanted to try lowering the pH of my water just a tad since there is a hard to pinpoint astringent-y type flavor to all of my beers, and I thought it might have something to do with too high pH during sparging. It's pretty subtle, but it seems to always be there.

I'm all for the treatment, I always treat my sparge water with Phosporic, and sometimes my mash water also if it's still high 5 minutes or so after dough in. I think you can get a Hanna handheld meter for around $40 and eliminate the pH guess work.

 

[scone]

Honestly, I don't really want to deal with the pH meter and the calibration and proper storage issues that come with it. ;-) Yet anyway.

I did just look up the last three quarterly water quality reports in Austin, and the total hardness has been between 94 and 111, with a pH of 9.6-9.8. I've got some reading to do I think, but off the cuff it seems fairly high for brewing water, and it doesn't seem like I'd be putting too much acid in the water with 20 mL of 10%. That being said, I don't fully understand the chemistry involved yet so perhaps I am.

 

[kylevester]

A pH of 9.6 to 9.8 going to the tap? Holy hell that is way off what it should be. Water should be about ph 7 at your tap, with EPA secondary regs (which don't need to be followed) of 6.5 to 8.5. I'm stunned it's 9.7 on average.

That's certainly the reason you're getting astringency in all your batches if you've not treated prior to this. I use pH 5.2 stabilizer for all my hot liquor, and you may want to do this if you're not gonna invest in a pH meter. Without a pH meter, you can make an educated guess about how much acid to add, but if you end up with a day of pH 8.5 water and you're adding for pH 9.5, well then you're gonna over acidify. So, play it safe and use a buffer or invest in the pH meter. BTW, get a quality pH meter from a lab supply and not Amazon.

 

[scone]

A pH of 9.6 to 9.8 going to the tap? Holy hell that is way off what it should be. Water should be about ph 7 at your tap, with EPA secondary regs (which don't need to be followed) of 6.5 to 8.5. I'm stunned it's 9.7 on average.

Yeah it seems pretty high, but I've heard from multiple sources that Austin is considered to have pretty good drinking water quality. Like some of the best for a metropolitan city...?

So I plugged in my latest water report into the EZ water calculator (http://www.ezwatercalculator.com/) and I'm just barely out of bounds for the ideal room temperature mash pH using my tap water as is (I assume it provides room temperature mash pH results since that's the temperature people read at with pH meters?). There's no phosphoric acid addition possibility with the spreadsheet, but adding 20ml of 10% lactic acid to the mash water section yields a predicted mash pH inside the ideal limits but at the bottom end. Hmm.

I realize that if my water was a bit lower in pH to begin with I could have dropped below the recommended limits. Then again, I think the spreadsheet assumes that I am adding all that lactic acid to the mash itself, when in reality I spread it across all of the water I used to brew (including the 2 batch sparges). I've also read that phosphoric acid drops the pH a bit less than an equal amount of equal concentration lactic acid, so I would assume that if the city's water report is reasonably accurate, I'd have been within 5.2-5.4 pH.

 

[DoubleBee]

For what it's worth, I'm running into that same astringency issue with filtered Austin tap water. It's never horrible, just an astringent twang hanging out on the palette. I figured it's either mashing too long, sparging too hot, or the mash pH. I've got the mash down to an hour, the batch sparge water capped at 175 (grain bed never topping the mid 160s), and now I'm measuring pH to see if that's it.

The part that's troubling to me is that the calculators are giving me 5.6-5.7 for room temperature pH levels, depending on the grain bill, which should have me a little high at mash temps, but the strips are testing consistently in the 5.2-5.3 range. So according to those, I should be golden, but yet every brewer in town uses phosphoric to treat the incredibly alkaline water here. I've actually looked at the charts on the fermenters at South Austin Brewing and 512, to confirm this, and they both use phosphoric to get mash pH down (South Austin adds calcium in various forms, too).

I guess the strips could be off, and I could just follow the B'run water suggestions for the 88% lactic I have (1/3 teaspoon), but I'm hesitant to mess with fairly good brewing water.

Side note: Anyone in Austin use gypsum to get the calcium up from 11ppm? Does it make a noticeable difference?

 

[fpweeks]

if you didn't get a good measurement of the pre/post boil volumes how can you be sure what your efficiency was?

 

[tinytowers]

if you didn't get a good measurement of the pre/post boil volumes how can you be sure what your efficiency was?

Just out of curiosity, why would a pre-boil volume be necessary at all?

 

[kiblerjd]

I would think the pre boil volume would give you the most accurate measure of efficiency. That's you "conversion" efficiency. If you are calculating it after the boil you are measuring the efficiency of your entire process and there is a ton more error involved there. If you know exactly how much grain you use and how much water you ended up with after the mash and sparge, if you take a gravity reading that tells you how well you did pulling out the sugars. Just my opinion obviously I'm by no means an efficiency expert.

 

[fpweeks]

^ This. IF you wait until its in your fermentor, i would call that brewhouse efficiency, because it takes into account losses in the kettle, chiller, etc.