Rubbish efficiency, or dodgy hydrometer?

[PoleyEire]

Hey all,

I'd appreciate a bit of insight from those a little more in the know here, if you would be so kind. =)

I've been AG brewing for a few years now, mainly just bumbling through and coming out with passable beers, but more recently I'm getting my act together with regards to proper measurements etc. With that disclaimer out of the way, please forgive any clangers following!

So I brewed a sort of double IPA that I've tried a couple of times in the past with great results. I tried a new supplier this time as they've opened locally and have a great selection. Brew went according to plan as usual, but the gravity post-boil came out at 1.032! While I've never measured my efficiency, I've never had this sort of low result before, even with this recipe. The beer came out the dark colour it usually does and it's fermenting away quite actively, I just find it very hard to believe that it could be so low.

The mash was at 65C for an hour and kept its temp throughout. I use a coolbox type arrangement. I'll list below the grain bill:

3.45 kg Munich Malt
2.30 kg Maris Otter Pale
0.25 kg Caramel/Crystal 90°
0.25 kg Caramel/Crystal 140°
0.25 kg Carapils Malt

12.8 AAU Chinook (60min)
1.40 AAU Cascade (30min)
3.20 AAU Chinook (30min)
5.50 AAU Cascade (10min)
9.60 AAU Chinook (Dry Hopped for 2 weeks)
4.20 AAU Cascade (Dry Hopped for 2 weeks)

Wyeast American Ale 1056

Beersmith has this at a much higher SG and the last time I brewed it, it came our around 6.7%ABV, the only things I can really put this down to are a poor grain crush from the new suppliers or a knackered hydrometer (it's never let me down before and hasn't taken a knock or anything.) Has anyone any ideas? I really like this beer but I'd rather it wasn't a soft drink.

Having read the previous threads regarding efficiency, I'm going to get a good read on it the next time I get a brew on, might give me a bit more information to work with.

 

[ImNoExpert]

New grain supplier: new grain crush.

That's my guess.

You can test your hydrometer for accuracy at its calibration temperature and some distilled or RO water. But my guess is it was the crush.

 

[PoleyEire]

Might be time to invest in a grain mill in which case. =/

 

[kh54s10]

Check the hydrometer. 1.000 in distilled water, very close to that in tap water. If that reads OK then you might want to take another reading to see if the first was in error.

If that is still low, your grain crush is probably to blame. If it is the crush it would have to be barely crushed at all.

The only other problem would be with temperature but to make that big a difference in gravity the thermometer would have to be WAY off.

 

[jparrette]

2 pearls of wisdom from my hero Tasty McDole....

You should always take your PRE-boil gravity after you've collected your wort. At that point, you can add DME if you're low or water it down if it's high. You should also know your system well enough to know your boil-off rate and be able to guess your final gravity. I know on mine, with a 90 minute boil, I usually gain 10 or 11 gravity points through evaporation. So a 1.050 pre-boil will end at 1.061.

I've seen hydrometers be off a few points, but not more than that. I suspect the grain crush is your problem. I tiny change in the crush can send your efficiency hugely. My efficiency settled down once I got my own crusher and got it dialed in.

Happy brewing!

 

[PoleyEire]

I've just tested it again, its been fermenting for a day now and its still around 1.025, so I suspect the reading yesterday may have been off. The hydrometer is reading 1.000 in tap water (I'll have to wait til I get back into work to try it in distilled water), but I suspect it's ok. The thermometer is fine, it's been well tested!

That's what surprised me, I couldn't believe that the grain crush could make such a difference as it did appear to be at least partially crushed. Still, I'll get (or make) myself a mill and do it at home from now on. That's a good tip re: gravity before the boil. I'll add a few values into my brew sheet for the next one. Bit disappointed in the supplier, they've such a great stock too.

How does one measure brewhouse efficiency? I'm not going to get too hung up on it, but I'd like to know if it's atrociously low.

 

[hanuswalrus]

Here's a calculator for brewhouse efficiency that also has descriptions of all the fields of entry

http://www.brewersfriend.com/brewhouse-efficiency/

 

[eric19312]

I'd add that an inexpensive refractometer makes it easy to get that pre-boil gravity. I calculate pre-boil volume and gravity when I design a recipe so I can check everything is on track at end of lautering.

 

[hanuswalrus]

Would be nice to have a refractometer.. One day I'll get one. For now, I just take a hydrometer reading and use this calculator to adjust for temp correction: http://www.brewersfriend.com/hydrometer-temp/

I've actually tested this calculator before using samples at about 120F and samples at the proper 68F.. the calculator has always been right on for me. I think one time it was off by 1 gravity point.

 

[PoleyEire]

This is all brilliant folks, thank you.

 

[dwhite60]

That's what surprised me, I couldn't believe that the grain crush could make such a difference as it did appear to be at least partially crushed.

This may be your answer. Did the crush look significantly different
from what you've been getting? You're sure they did grind it?
"At least partially" is not conducive to high extract percentages.

Mis-communication happens.

All the Best,
D. White