Taking Sg

[Brightsbane]

Hi, I'm new to the site and this is my first brew. I'm brewing a standard K&K Coopers Australian Draught. Initial SG was 1046. The brew is currently at about 96 hours and its been a hot few days in Brisbane. I've only been able to get the temp range between 24 and 26, (using wet towels and fan - as recommended by other users) althought when I cast the yeast I had it at about 21. Fermentation has slowed right down and it bubbles once at approx. every 3.5 minutes.

My problem is getting an acurate SG. I carefully tap out a sample into the tube provided in the kit and then insert the hydrometer. I bob it a couple of times and spin it and make sure it's not touching the sides and the reading at the top of the meniscus was at first 1014. I fugured I would retake the reading in the same sample a couple of times so I bobed it and spun it again and the more I did it, the lower the reading I got. After about 5 minutes I eventually I got a reading of 1008.

What am I doing wrong? What is the proper technique?

Thanks,

Peter.

 

[Adamt]

1.008 is probably the right reading.

The problem is; during fermentation carbon dioxide is produced. Some of this dissolves into the beer (albeit not much at fermentation temperature) and the rest goes through the airlock. When you take a sample in to your hydrometer tube there is usually some carbonation in the sample which can affect hydrometer readings. Bobbing the hydrometer and spinning it is aimed at dispelling most of the carbonation to get an accurate reading.

If you are unsure, leave it for another day or two and measure the SG again, if it reads the same, it is ready to bottle!

Cheers.

 

[mika]

I always have trouble with those pesky bubbles in the way, so I fill the tube right to the top and then when I plunk the hydrometer in it displaces some beer and most of the foam and I generally end up with a no bubbles reading.
It's probably not so important how the SG is measured rather that it is measured the same way each time you take a reading and that you base your knowledge of your beer on that. As with everything in brewing it's a case of YMMV, that's why you can ask 2 brewers the same question and get 3 different answers.

 

[pint of lager]

That pesky dissolved CO2 makes it hard to take an accurate reading. It is even harder when taking lager readings that have been fermented with a lager yeast at lager temperatures. There is more dissolved CO2 in cold liquids.

If you bottle too early, this extra dissolved CO2 can cause problems with overcarbonation.

This is how I take a reading.

Tap a sample into your sample tube. Use the end of a teaspoon to give the sample a really good stir. Scoop the foam off with the teaspoon. Then use the hydrometer. For good measure drink the sample, don't pour it back into the fermenter.

 

[clarkey7]

This is how I take a reading.

Tap a sample into a small jug. Not too much - you don't want to waste your precious brew.

Swizzle the jug around in a circular motion.
This does 2 things.

1) helps to bring dissolved CO2 out of solution and
2) bunddles all those pesky bubbles together.

You should now be able to pour "non-bubbled" beer into the Hydrometer sample tube.

You may need to repeat swizzling step to get a clear sample depending on how much beer you tapped off in the first place.

Then use the hydrometer. If your feeling scientific, average 3 readings.

Never pour it back into the fermenter.

Good luck with this and future brews....

Cheers

PB :beer:

 

[Keifer]

Im back doing kits these days instead of AG and if do take a sg reading i just fill the tube and leave it while i get my stuff ready to bottle/keg. I rarely take sg's anymore because i make most of my beers to be at 4.5 - 5 % alc and just leave them for at least a week. Never had a prob.

 

[Brightsbane]

Thanks guys, thats great advice. For my next reading I'll settle the sample a bit first and see how I go.

Cheers.

 

[RobboMC]

Did you consider that the spinning and tapping might have done very little to help change the reading?

The critical info in your questions is that you got a good reading 5 minutes later.

So maybe you have yourself a 'process', take the sample and wait 5 minutes.
As you have found out, hydrometer readings are rough at best.

 

[warra48]

I don't always take a reading (I've forgotten to do a few on filling the fermenter), but when I do, I do one at the start. I leave my ale brews for 2 weeks, then bottle. I take a reading at bottling time, but only to work out the alcohol level for my records.
For lagers, I do the second one on racking, and a 3rd one on bottling after lagering.
It's not really that important an issue. Some people don't bother at all, and just leave their beer for 2 weeks in the fermenter. It doesn't change the quality or strength of your beer. After all, we are not commercial brewers, so we don't need the precise records to extract the last few cents worth of efficiency from our grains.

 

[paul]

When I used to use a hydrometer I just steralized the hydrometer and throw it in the fermenter and leave it in there for the whole brew.