Hydrometer question

[Flem]

I discovered something this evening that I haven't experienced before. I was taking a SG reading on a juice bucket. I had just stirred it. I put the hydrometer in it and it read 1.030. I left it in the wine and went on to check the temperature and do a couple of other things. A few minutes later, I checked it again and it read 1.021. Normally, I would check it and take it out immediately. Why the disparity in the two readings? I would think the two readings should be exactly the same. Thoughts?

 

[rob]

my guess is there were some bubbles stuck to it, I always give my a little spin to dislodge the bubbles

 

[Flem]

No bubbles. I've taken readings dozens of times.

 

[Runningwolf]

Duh thats simple. It was more excited the first time it saw you. Second time around it was the same old face. LOL

 

[Wade E]

Im guessing that since you just stirred it the wines sugar was more concentrated in the middle.

 

[cold]

Fill up the primary with water, let get to room temp and then test

I suspected my hydrometer was out, so I filled up the primary with just water, and let the water sit until it was equal to room temperature. Then I put the hydrometer in. Sure enough, it read exactly 1.000

But even if your hydrometer is out, you would just add/subtract that amount from what it says on the scale.

ie: If it would have read 1.005, then I would subtract 0.005 from all readings.

And even if a hydrometer is out, when it stops moving for three days, fermentation is pretty much done.

 

[Flem]

All my hydrometers have been calibrated. I checked it again today. Difference over a 5 minute period was about .003 lower for the second reading.

PS This isn't a question as to whether or not fermentation is complete. Thanks, though.

 

[robie]

If when you insert the hydrometer into the wine, you do not spin it, there will be bubbles stuck to it. As already mentioned, over time those bubbles will turn loose, slightly lowering the hydrometer.

As Wade said, if the wine had just been stirred, by the time it settled again, the hydrometer reading could change.

Some CO2 was released during the time the hydrometer was setting in the wine. That could also make a slight difference, just not the difference you observed.

 

[jdeere5220]

Why the disparity in the two readings? I would think the two readings should be exactly the same. Thoughts?

Hello Flem,

You've obviously covered all the basics. I wonder if this is a new insight we should all consider. Is your wine warmer or colder than your hydrometer? Do you maybe store the hydrometer in a different location than your wine?

I'm wondering if your hydrometer is changing temperature, and I'm wondering if the change in temp causes the reading to change over time as your hydrometer reaches the same temp as your wine. I would expect it to, since it's made of glass it must expand and contract as it warms and cools.

Otherwise I wonder if the viscosity of a must is not as uniform as we tend to think. Maybe there are pockets of higher sugar and lower sugar that drift around. Not sure on that one.

I think I'll try giving my readings 5 minutes and see if I notice any changes.

 

[buddy]

I have found that if I take a reading of a wine that is actively fermenting in a primary or secondary, the CO2 that is given off will throw out my readings. After repeated trials I couldn't get two readings the same.
Now what I do is put some of that fermenting wine in the flask that comes with the hydrometer. The wine is still fermenting in the flask but the volume is greatly reduced so there is a lot less CO2 that could interfere with the readings.

 

[Runningwolf]

This wine thief from Fermtech is fantastic also for hydrometer readings. I find it as a great around utensil and inexpensive. There are sometimes though that I do still use the hydrometer flask.

 

[Ernest T Bass]

I have a question on reading the hydrometer. When I put the hydrometer in the test tube that came with it, I spin it and it always sticks to the side of the test tube. If it reads 1.000, I can push it down and it will stay at .990 or .995 or if I raise it up to 1.005 it will stay there.

 

[jdeere5220]

Your right, if the hydro is clinging to the side you can't get a good reading.

Rotate the test tube 1/4 turn and give the hydrometer another spin. Repeat until it hopefully doesn't stick. The test tube has to be standing straight and down and I know mine leans just slightly, but I can usually rotate it until the hydrometer will come to rest without clinging to the side.

If you can't get it to work you might have a hydrometer that leans, which means you are probably going to have to try another.

 

[djrockinsteve]

I have fould that my hydrometer always spins away from me being able to read it. I now try to read the back end so it now rotates where I can actually read it.

You could try after inserting the hydrometer place your 2 pointer fingers on either side of the hydrometer keeping it in the center. Work the unit off of the sides and then slowly back away your fingers.

I have found that doing this I am able to get the unit in the center of the beaker away from the sides. It will take a minute or so to allow the wine to stop moving thus allowing the unit to be still.

 

[ibglowin]

Remember that when your juice is in the middle of fermenting out, ethanol is lighter in density than the unfermented must. If you happen to hit a pocket of fermented juice the reading may drop. As it moves out into a pocket of unfermented must it will rise a bit with the higher density. Its always good to give the primary a little stir to mix things up for a more uniformly distributed must reading.

 

[jdeere5220]

I have fould that my hydrometer always spins away from me being able to read it. I now try to read the back end so it now rotates where I can actually read it.

 

[ibglowin]

Yep, you have to outsmart the hydrometer at times!

 

[Flem]

Or the "hydrometer". LOL

 

[ibglowin]

Hehe......

I use a Hygrometer quite often in my real job!