High FG or measurement error?

For the third brew in a row, fermentation has seemed to stop at 1.018-1.020. All three had predicted FG's of 1.014-1.016. Two were extract brews using different brands of extract. One was an ESB and was relatively pale, and one was an American brown. Now, I've brewed my first AG batch, a Northern English Brown. The measured OG was 1.053. The SG seems to have stopped at 1.019. Fermentation temps have all been between 68 and 72. All used different yeasts and all had a 1 qt. starter. Each fermentation started rapidly (3-5 hours) and was quite vigorous for the first couple of days (one blew the lid off a 6.5 gal bucket fermenter). The two extract brews were both bottled. One's been in the bottle over a month and the other for 2 weeks. No gushers, no bottle bombs, and the flavor doesn't seem too sweet.

I just bought a handy refractometer on E-Bay for about $25 shipped. I calibrated it using distilled water as instructed. Unfortunately, it came after my last brewing session, so I didn't have the chance to use it for measuring my OG on the last brew -- I used the hydrometer for that. Being curious, I used the refractometer to measure my SG after fermentation, plugged the OG reading and refractometer reading into Beersmith and was given a gravity reading of 1.015 which is the finishing gravity for the recipe. Morebeer's spreadsheet gives the same result.

Now I'm confused. Everything I've read says that the hydrometer is more accurate than a corrected refractometer reading after fermentation (except Morebeer who begs to differ). Yet I find it hard to believe that three vigorous fermentations in a row using different ingredients and different yeasts got stuck at the same place. Yet, when I calibrated my hydrometer using distilled water it appeared more or less accurate. Am I doing something wrong in my brewing? Is the refractometer reading right? Am I messing up my hydrometer readings? Could my hydrometer have some kind of error?

If you have any insight, please send it along. Thanx.

Sorry you're having troubles... Nothing that you described "jumped" out at me as a huge cause.... you mentioned you used 3 different strains of yeast, what were they?

From what you've said, you have indeed done everything to a 'T'. +1 to you for using a starter, too.

I'll keep brainstorming.

chriso said:

Sorry you're having troubles... Nothing that you described "jumped" out at me as a huge cause.... you mentioned you used 3 different strains of yeast, what were they?

From what you've said, you have indeed done everything to a 'T'. +1 to you for using a starter, too.

I'll keep brainstorming.

Click to expand...

Thanks for thinking about it. All the yeasts were White Labs -- WLP001 California Ale Yeast, WLP005 British Ale, and WLP023 Burton Ale Yeast.

Were your OG's as predicted? If they were high or low (with Extract primarily due to brewing less or more than a 5 gallon batch), then the FG will be off as well.

have you checked the hydrometer in water? Corrected for temp?

I did check the hydrometer and did correct for temperature. The OG issue could have something to do with it. On two of the brews, my OG was 2 points higher than I expected - 1.061 instead of 1.059 and 1.071 vs. 1.069. Hard to say on the AG since, being my first, I had no idea what efficiency to expect.

Perhaps I'm reading the hydrometer wrong. The angle you view it makes a difference, I suppose, but not by as much as I'm getting.