Glass Hydromter Readings Changed?

[MaltyWalty]

So, I on my last brew, I found my OG was 7 point higher than expected. I was completely cool with that since it was a new recipe and an experimental beer, anyway. Today, I took readings of two beers that I have in the fermenters that should have finished by now. Both were reading much higher than the expected F.G. I haven't had attenuation problems in the past, so I am thinking that I have an equipment issue. I do recall my hydrometer taking a rough fall just before the last time I brewed, so much so that I was surprised that it did not break. I did a distilled water test and found it at 1.002, pretty close. So, is there any chance that the hydrometer can become way uncalibrated from a fall such that the gravity readings are off and more exacerbated the higher its gets away from 1.000? Anyone experience this? I'm not taking any chances and replacing it on the next brew. Just sucks that I have no idea what my previous two brews really are.

 

[Coastalbrew]

I've not experienced a non linear gravity reading error like what you are describing. But the first thing that comes to my mind is what is your sample temperature? And what temperature is your hydrometer calibrated to? Also it may be worth checking your hydrometer for liquid inside. If it cracked when it fell and liquid got in that will also affect the readings. Flip it upside down and see if anything runs to the other end.

Most of my beers that have come in over the expected og have finished over the expected fg. Have you tried running the actual numbers through your brewing calculator? You may find that the beer is actually spot on based on the actual gravity readings.

Cheers!

 

[Jtvann]

There's generally a slip of paper inside the tube with markings. If it took s hard enough hit, yes the paper can slide causing off readings. I'd expect it to break before that happened, but who knows?

 

[schematix]

All 3 of the standard $7 LHBS hydrometers i owned had this happen.

The solution was to get a set of 3 precision lab grade hydrometers. They are built much better (and precise) than the normal crap. Expect to spend about $100 for a set of 3, and they are worth double that. Depending on the beers you make you may be able to get away with 2 instead of 3.

A digital refractometer is another $100 well spent. Once you've taken the first accurate OG measurement you can get very accurate FG measurements with small samples. I rarely take an FG measurement anymore now that i have confidence in the tools.

 

[MaltyWalty]

I've not experienced a non linear gravity reading error like what you are describing. But the first thing that comes to my mind is what is your sample temperature? And what temperature is your hydrometer calibrated to? Also it may be worth checking your hydrometer for liquid inside. If it cracked when it fell and liquid got in that will also affect the readings. Flip it upside down and see if anything runs to the other end.

Most of my beers that have come in over the expected og have finished over the expected fg. Have you tried running the actual numbers through your brewing calculator? You may find that the beer is actually spot on based on the actual gravity readings.

Cheers!

My sample temps have been in the 65ºF to 70ºF and I did adjust the reading for temperature. Unfortunately, I am inclined to believe the OG numbers (pre-drop) over the FG numbers. I did a taste test and one of the brews that the calculation shows is 1.5% ABV is by taste, not so... not a scientific measurement, but the best I have at the moment.

 

[MaltyWalty]

All 3 of the standard $7 LHBS hydrometers i owned had this happen.

The solution was to get a set of 3 precision lab grade hydrometers. They are built much better (and precise) than the normal crap. Expect to spend about $100 for a set of 3, and they are worth double that. Depending on the beers you make you may be able to get away with 2 instead of 3.

What lab grade hydrometers do you use? This sounds like something worth investing in.

 

[schematix]

What lab grade hydrometers do you use? This sounds like something worth investing in.

I'd have to go dig for the exact one i have, but there are a lot out there if you google narrow range hydrometers. It's similar to this: https://www.morebeer.com/products/brix-hydrometer-0-12-correction-scale.html

The key specs are:
-Marks in 0.1 Plato (about 1/4 of an SG point) increments
-Integrated temperature correction scale
-Narrow range (mine are 0-8.5 P, 7.5-16.5 P and 16-24.5 P)

Get the ones that suits your brewing. At a minimum you need one for measuring FG (range closer to 0) and then a mid range (~8-16P). I've only ever pulled the highest end one out once when i did a huge doppelbock and got it to 16.7P.

 

[Wayne1]

These are a bit less expensive:
"Hydrometers are manufactured to the exacting specifications provided by NIST, ASTM/API and IRS and are calibrated against standards traceable to NIST. A certificate is provided with each hydrometer assuring that the user receives a quality instrument."

https://www.labdepotinc.com/p-61276-hydrometers-brix

 

[IslandLizard]

What lab grade hydrometers do you use? This sounds like something worth investing in.

Although nice to have one or more precision hydrometers, I think it's overkill for most homebrew purposes, and they're just as or even more fragile. Being within 2 points is plenty close for me, and I've found that the FG can't be changed anyway.

My $8-10 hydrometer from the LHBS is pretty decent and good enough for me. Now I hate those multi-color ones that are included with most kits, so I carefully selected one that has a simple white scale (Brix and SG, maybe a 3rd I never use), easy to read deviations, straightforward, no nonsense. It has a fairly long scale, about 30% longer than the crappy color ones. That gives me just enough precision. Oh, it's off 1 point (reads higher), so it gets subtracted in my mind. If I break it I hope I can find one that's like it or close. Maybe buy a 2nd for insurance...

 

[IslandLizard]

Hydrometers are very simple instruments. It's all about displacement (and temperature).
If you get 1.002 in distilled water it may be the positioning of the paper scale in the factory or maybe it got loose and moves around between readings. Check for the little (red) lacquer dot on one of the edges that holds it in place.

Most are made from sealed thin glass with glued down steel pellets or some other heavy substance in the bottom. They tend to break, shatter, not crack. Now Northern Brewer sells plastic (acrylic?) hydrometers which are a bit more resilient to small drops and bumps, but not very well made or precise from what I've heard.

You could check calibration or accuracy in your desired range with a known % sugar solution.

As long as your hydrometer checks out, I have the feeling your beer has finished with a higher FG. Maybe due to a bit higher mash temp? Different grain? Yeast health, oxygenation, etc.

Now having a good, fast, and reliable thermometer would be on top of my list, far above a precision hydrometer, or electronic refractometer. I splurged on a Thermapen (Mk4) at an open box sale, 6 years late IMO. I do like to nail my mash temp within a degree, max 2 only for a short time.

 

[schematix]

My precision hydrometers have an internal mark where the the paper lines up, so you'll know if it were ever to slip.

You can get away with less... 2 points is too much for me. The problem was i never knew if i was plus 2, or minus 2.

The precision ones are just built better so they don't have the paper slip issue.