[Iliff Ave]

HELP!

The average brewhouse efficiency of my last 5 batches has dropped about 5 percentage points and I'm in need some help troubleshooting. I batch sparge in a 10 gallon round igloo cooler and average around 77% and into the mid 80s for session beers. I have changed nothing with my process.

Actions taken:
*My old hydrometer broke. I bought a new cheap one from amazon and that was when I first noticed the drop. I bought another one from my LHBS and it reads the sames.
*crush looks fine. Last night I readjusted the gap and made sure it is where it normally is. I also double crushed.
*thermometer is good. I calibrated it at freezing and boiling temps

My next thing to look at is water. I do not have a pH meter and have always just used bru'n water without problems. I'm worried my water supply profile has changed though it would have to be pretty drastic to make a big impact. I normally have an estimated mash pH around 5.3. May be time for another wards lab test

Last night I did notice that my mash temp seemed to drop more and quicker than usual. I usually mash at 150F because that's what works for me. By the end of the hour the temp was around 144/145F. I normally don't notice a drop of more than a couple degrees throughout the mash so I find this very strange. Could this drop in temperature be the culprit? I have been getting higher than expected attenuation around this same time period.

The beer I brewed last night normally comes in around 78.9% brewhouse. I got 74.3%. It bugs me.

Any thoughts or guidance?

[Megary]

Starting with the obvious...

Are you sure your OLD hydrometer was accurate? If it broke, maybe it was developing a crack and was giving you false readings?

[rburrelli]

Have you made a change in your base malt for these batches? Just a thought.

[Iliff Ave]

Starting with the obvious...

Are you sure your OLD hydrometer was accurate? If it broke, maybe it was developing a crack and was giving you false readings?

It's possible. I had calibrated it as accurate at some point in the past so I think I just assumed it was good to go when it broke. Good thought.

[Iliff Ave]

Have you made a change in your base malt for these batches? Just a thought.

My standard base malt for pretty much everything is Dingemanns Pils. That has not changed though I have done some batches such as Marzen which didn't include much...

[denny]

Have you made a change in your base malt for these batches? Just a thought.

THIS. Unless you're using the same malt from the same lot, you're comparing apples and oranges

[Iliff Ave]

Have you made a change in your base malt for these batches? Just a thought.

THIS. Unless you're using the same malt from the same lot, you're comparing apples and oranges

I have not changed my base malt. The only beer that wasn't primarily pilsner malt from the same bag as before the noticed changes was a Marzen which still suffered the same result. I will take a look at the specs of this bag's lot compared to last.

[brewthru]

Hydrometers are calibrated at different temps. Believe 60F and, I believe, 68F. Sure you are using the correct calibration temp for the new hydrometer?

Malts. Malt analysis changes. Just because a certain malt produced a certain gravity last time is no guarantee a new batch of the same malt will do the same this brew. Also, malt with same name from different maltsters have different specs. Brewing software relies on the malt specs in the software. Unless one has changed the brewing software malt specs to match the current malt specs this may account for differences (estimated vs actual).

Mention the mash temp. I was just getting ready to ask about differences in mash temps. Any way to insulate the kettle to keep the temp at or near the desired temp (in this case 150F)?

pH? How is the water pH? Has the water pH changed since getting higher efficiency?

Too quick sparge. Has the sparge time changed since getting the higher efficiency? Quick sparge, while good for us (meaning saving time), really is bad for extracting fermentables.

[chinaski]

If your efficiency stays pretty constant, then I wouldn't sweat it and would move on.  You can still adjust recipes and know what you will get on brew day, which is what I would want.  How much grain is the difference between this new efficiency and the old one for most recipes?  I bet it ain't much.

[Iliff Ave]

Thanks all

[Iliff Ave]

Update. The most recent beer has finished at 1.007 for an attenuation of 86%. This is extremely high for me. My drop in mash temp over 1 hour may not be causing an efficiency issue but seems to be causing higher attenuation.

[brewthru]

Using the exact same yeast?

[Iliff Ave]

Using the exact same yeast?

No but a yeast I've used many times and has never gone above 80%. I believe it got me 79% attenuation from the same grist last time I brewed this beer

[brewthru]

Fermentation temps exactly the same?

[Iliff Ave]

Fermentation temps exactly the same?

Yes. I use a limited variety of yeast strains. Anything above 82% is an anomaly based upon the beers that I brew