Refractometer Vs Hydrometer

This has been probably discussed a thousand times on this forum so apologies but I am having some difficulty with my gravity measurements.

I am currently brewing an Australian Sparkling Ale and my target OG was 1.048. I took a reading with my new refractometer and it read Brix 12/ 1.047sg, very close to my target. I also took a reading with my hydrometer which read 1.045 which was close enough for me.

Now I'm trying to track my FG, hydrometer reads 1.010 and my target is 1.009 so very close again, but when I take a refractometer reading this is coming out at 5 Brix and using the tool in Beersmith to calculate an FG is correcting it to 1.003 which is pretty off.

So really my question is why when my readings started so close at the begining of the brew have they drifted apart? Are refractometers too unreliable to take FG readings?

Thanks in advance for your comments.

 

Yes

Explanations to follow

 

Refractometers simply don't work in the presence of alcohol. There are many calculators that you can use to convert your refractometer reading post fermentation but they all make some assumptions and are rarely as accurate as the cheapest hydrometer.

Refractometers are most useful for determining how much sugar is in fruit. For example, if you are a farmer and want to know if a particular grapevine is ready to harvest, just squeeze a drop of juice on it and look up. Otherwise you have to rely on good ole taste and feel.

 

I had the same issue come up recently. I was brewing NB Dragons Silk extract kit with an original gravity of 1.080 and a final gravity of 1.018 target. After two weeks of it sitting at 1.045 using my refractometer to measure the gravity, I called NB. I've been using extract kits for a few years now, and they have always hit the target. This was my first high gravity beer, and I thought maybe I had a stuck fermentation. First thing the guy asked was "how are you taking the readings, refractometer or hydrometer?" He then explained that refractometer is great for original gravity, but lousy for final gravity, especially in high alcohol beers. I took the reading with my hydrometer and it showed 1.020.

The plus side of using a hydrometer to check final gravity is that it gives me an opportunity to preview my beer. I've been brewing for 7 years now, and this was something I had never come across on the forums. Doesn't mean it's not out there, more likely, I just didn't pay attention to it.

 

It is pretty simple.. You need both. Refractometer for use before fermentation and hydrometer for use after fermentation.

 

I love my refractometer for brew day since I'm taking many readings (first runnings, second runnings, pre-boil, post boil). But after brew day, it stays in the box until the next brew day.

Sanitizing a taking samples with a wine thief is a bit of a nuisance, but that's just part of the process. Plus I then cold crash the sample and taste it, which gives me an interesting view into the evolution of the beer as it conditions.

 

I initially used both, but after multiple comparisons showed the my refractometer was consistently within a point or equal to my hydrometer, I only use the refractometer now. It's easier to use and has been just as consistent for FGs when used in conjunction with the Sean Terrill online calculator. YMMV....

 

Most of the time I don't need an accurate FG. All I really need to know is that it is stable. So I will use my refractometer in that situation. In fact, if my fermentation hasn't shown anything abnormal, I often don't even take an FG reading. But I have and use both as the situation calls for.

 

I have been using my refractometer mainly for determining my yeast starter OG (never read FG just watch it in action) and on brew day as well. When taking any reading of my fermentation I use a glass turkey baster and my hydrometer.

 

Thanks for all the comments and advice. A lesson learned here for me.