[a-a-ron]

Hi, all. Here's my latest issue. I am fairly new to this brewing thing. About six brews in. I brew 2-2.5 gallon batches, and I usually make a starter. My obsession right now is to make a really good NEIPA. So here's the thing: after I pitched my latest batch (London Ale III), it was off to the races, dropping from 1.070 to 1.020 in 36 hours. Today, on day four, it's finishing at around 1.009! My calculated gravity was 1.017. I mashed at 152, which is fairly conservative as you know. Many mash lower for a NEIPA, around 149. I also know my refractometer is correctly calibrated and adjusted. And I am pretty sure my thermapen is giving me correct mash temps (though I will definitely check next time).

So I am led to wonder whether my tendency to make a starter for my small batches could be causing me to over-pitch, resulting in over-attenuation? I use Mr. Malty, and it usually says (with my average three-month old yeast) to make a 1-liter starter. I do use a stir plate. As far as oxygenating my wort, I tend to use a whirlpool wand and then shake the fermenter.

In fact, when I go back and look at my brewing journal, my beers USUALLY finish too dry. Any thoughts would be appreciated!

[denny]

It could be the yeast, but there are other factors, too.  I had a run of over attenuated beers and finally discovered that my thermometer was miscalibrated so I was mashing at a lower temp than I intended.  Not that that's necessario y what's happening to you, but you need to consider all possible factors.

[a-a-ron]

Thanks. I'll definitely double-check my Thermometer.

[Bob357]

An OG of 1.070 and FG of 1.009 works out to ~ 86% Apparent attenuation. I'd expect somewhere in the low to mid 70% range from 1318, depending on wort composition/fermentability. 
Using the information you posted, the starter is almost twice the size needed for 2.5 gallons of 1.070 wort, but it wouldn't be to blame that low of an FG.
A lower mash temperature would account for about 1.25 gravity points per degree FG. so would have to have been about 8 degrees low, or ~144 degrees to cause that much difference.

Not knowing the pre and post boil volumes and the accuracy of your measurements, or estimated volumes, I'm sticking with measurement error and possibly mash temperature and/or yeast to lesser degrees.

[MDL]

If you are using a refractometer to measure final gravity then confirm your calculated measurement with a hydrometer before looking any further.

[denny]

If you are using a refractometer to measure final gravity then confirm your calculated measurement with a hydrometer before looking any further.

A refractometer would measure high not low, right?

[tommymorris]

If you are using a refractometer to measure final gravity then confirm your calculated measurement with a hydrometer before looking any further.

A refractometer would measure high not low, right?

IMHO, Refractometer for FG introduces too much room for error. You have to have the correct OG, correction factor, and trust the refractometer reading itself.

PS. Do the beers taste too dry? Because if they don’t you may just be chasing a number when the beer is good.

[majorvices]

To answer your original question, no: Overpitching will not over attenuate your beer. You can try a forced fermentation to see how fermentable your wort is ahead of time by overpitching and over aerating to see what your fg is. It may be a small bit drier but it will not be several points drier.

[MNWayne]

"Beers usually finish too dry"  By numbers or by taste?  You can't taste numbers, if you like the finished products, then don't sweat the numbers.  If it's just a numbers issue then using a hydrometer instead of refractometer will give you a more accurate FG.  If everything is tasting too thin, then you need to adjust your recipe(s) by adding unfermentables.

[Bob357]

"Beers usually finish too dry"  By numbers or by taste?  You can't taste numbers, if you like the finished products, then don't sweat the numbers.  If it's just a numbers issue then using a hydrometer instead of refractometer will give you a more accurate FG.  If everything is tasting too thin, then you need to adjust your recipe(s) by adding unfermentables.

If used properly a refractometer is just as accurate as a hydrometer. Refractometers have a bad rap that should have gone to the people who haven't a clue about how to use them. It's absolutely amazing how many people think you can, right out of the box, put a couple of drops on the slide and read the SG scale. Probably 75+% of the stalled fermentation posts. Many others don't know what a Wort Correction Factor is. Like any other tool, it only works as well as the user.

[MDL]

"Beers usually finish too dry"  By numbers or by taste?  You can't taste numbers, if you like the finished products, then don't sweat the numbers.  If it's just a numbers issue then using a hydrometer instead of refractometer will give you a more accurate FG.  If everything is tasting too thin, then you need to adjust your recipe(s) by adding unfermentables.

If used properly a refractometer is just as accurate as a hydrometer. Refractometers have a bad rap that should have gone to the people who haven't a clue about how to use them. It's absolutely amazing how many people think you can, right out of the box, put a couple of drops on the slide and read the SG scale. Probably 75+% of the stalled fermentation posts. Many others don't know what a Wort Correction Factor is. Like any other tool, it only works as well as the user.

I would love to know how to use one. I have both a digital one and a handheld one and I can’t seem to get stable OG readings so I assume without an accurate OG reading I can’t even try to use it to measure FG.

I do use my digital one during brew day and it seems to get me close but I always resort to the hydrometer to check the OG before fermentation. Any tips or links to how to use a refractometer would be greatly appreciated!

[Bob357]

Chilling a little wort down and taking the sample from the top as it clears really helps to get good contrast. A good overhead light source also helps, as does using a lens cleaning cloth on the sampling surfaces. Although I've read time after time that with ATC you can immediately get an accurate reading I find that, even at mash temperatures, allowing a minute can make a significant difference.

I've been using a refractometer for 4 years and compare readings with hydrometer readings quite often. I haven't seen a difference of more than .001, which I consider to be well within the margin of error, since I started cooling hydrometer samples to within 1 degree of the calibration temperature. Prior to that I found much larger differences when using temperature correction tables. The meniscus can refract light enough under certain conditions to make it very difficult to read the hydrometer too.

While most discrepancies are blamed on the refractometer, I see just as much evidence to disagree. IMO, if you have a quality refractometer that's calibrated, use a well plotted Wort Correction Factor (using the average of several samples of various gravities and colors) and follow the other steps I mention above, you can trust your readings to be accurate.

[chumley]

As a Phillies fan, as soon as I read the topic, I knew this thread was not going to be about Aaron Nola.