Strange hydrometer readings

[carmo100]

Hi all,

I've currently got my first ever brew fermenting, I'm using the Coopers DIY beer kit with the included lager. Now it's been sitting there for six days now and yesterday I took a gravity reading. It was very low, 0980 in fact, I figured that it must be pretty well done fermenting. I took another reading today, and it's dropped even lower, off the hydrometer scale even. Something tells me this isn't right. It was quite hot this week, and the temperature was at the higher end of what coopers recommended, but I would have thought the gravity would be higher than it should be, rather than lower. Is it possible that my hydrometer is screwy? Or is this not an uncommon occurrence?

Thanks!

 

[angle228]

Higher temps will give you a lower SG reading. Even so those numbers do seem very low... but what do I know I haven’t even been at this home brew stuff for a year.

See the chart here. Between 32F and 100F the difference is only .005 to .007
http://www.engineeringtoolbox.com/water-temperature-specific-gravity-d_1179.html

Now this is for pure water, so I don’t know what different sugars and ETOH will do to the relative change in SG vs. temp but I would imagine beer still behaves similar to water in that the changes will be pretty small... smaller than you are experiencing.

Would love to hear from an expert homebrewer to tell me if im right or wrong

 

[Captain Damage]

Your hydrometer may be broken or screwy. Test your hydrometer in tap water. It should read at or very near 0. Then mix up a solution with tap water and a little sugar. It should read higher.

How are you testing your sample? Are you testing in your fermneter (not recommended). You should test in the tube it came in or in a cylinder of similar size. Give it a good spin to dislodge any bubbles and wait about 10 minutes for the reading to stabilize. There will be a small correction for temperature, but that's generally on the order of a point or two, not the sort of off-reading you're getting.

 

[carmo100]

Thanks for the reply.
I'm testing in the supplied tube using the brew out of the tap on the fermenter. I put the hydrometer in tap water and it sank to the bottom, so I assume it's heading toward 0 (the markings only begin at 0.980) and then it floats in sugar water as expected.

The gravity of the brew is reading at around 0.970, if I estimate the distance up the shaft from the first markings. Is a reading like this completely out of the question?

 

[BobC]

in water it should read 1.000 some people shorten it to 0 since almost all readings are 1.###. Sounds like your hydrometer is broken.

 

[carmo100]

Ah, I see. Well then it looks like a problem with my hydrometer, I wonder if Coopers will replace it...

I did think it had read 1.000 originally when I gave it a test run in water straight out of the box. Good to know I wasn't imagining things. Thanks for that.

 

[Dougie63]

see if there is some liquid in the hydrometer

 

[carmo100]

Yeah, I thought about that. Trouble is it's all plastic and glued up tight (I'm fairly sure). There's no liquid coming out if I shake it or spin it. And there's no bubbles to indicate leaks when it is submerged. It's certainly strange that it was working and now it isn't. Oh well, gives me an excuse to go to the home brew shop to pick up a new one, and all the ingredients for my next brew while I'm at it

 

[BobC]

That's the problem it's plastic. Plastic lets air through it and the inside of a hydrometer is a vacuum. Make sure you get a glass one next time.

 

[carmo100]

Someone should tell Coopers that! But I'll make sure I get a glass one now, thanks.

 

[Captain Damage]

in water it should read 1.000 some people shorten it to 0 since almost all readings are 1.###. Sounds like your hydrometer is broken.

Sorry, my screw-up (you'll notice the time stamp on my previous post is 5AM). Yes, I meant the gravity of water should be at or near 1.000. But as others have said, it does sound like your hydrometer is broken, maybe cracked or leaking, or something. In any case you need a new one to get meaningful readings. The good news is that when brewing extract based beers it's highly unlikely that your original gravity (OG) was more than about half a point off of what the instructions said it should be (assuming you followed the instructions). But for the final gravity (FG) you will need a working hydrometer.

 

[luke2080]

There are a couple of threads on that Coopers hydrometer. Its a great hydrometer because its plastic (can't smash it to pieces - see the broken hydrometer thread) but they seem to have a pretty high failure rate. For some reason they don't test them going out the door despite the high fail rate.

If you contact them, they should replace it right away. I haven't read any complaints that they have not replaced faulty hydrometers.