Hydrometer & SG

[Mark Gillman]

I have just purchased a glass hydrometer from a home brew shop in Adelaide. Whats the best way of taking the first reading?

Iam thinking that I will wait till the propagation period is over...24 hours or so, then either:-

1. Take the lid off and after sterilising the Hydrometer drop its into the brew before it kicks off.
2. Take a sample from the tap into the storage tube it came in, then take the reading.

Any thoughts

[Wazza_wantsbeer]

Hi @Mark Gillman,

I use my glass hydrometer to measure final ABV for every brew, from all grain wort, fresh wort kits and BrewArt ingredients/BrewPrints.

First, to get your final ABV you need to take two measurements, one at the start (Original Gravity - OG) and one at the end (Final Gravity - FG) post fermentation. Then using a standard calculation or one of the many online ABV Calculators, you put in your Original Gravity and Final Gravity and click on a button and you get your final Alcohol By Volume percentage.

I have to say, if using the BrewArt ingredients, taking the first measurement gets a little tricky as it takes a while for all the dry ingredients to dissolve evenly throughout the water in the Droid.

How I did it was to follow the standard method of adding ingredients including yeast, and then let it sit for around a day or so. However, before taking a sample, I would look thru the viewing port to make sure there isn't any dry powder on the surface. Then I take a measuring jar and from the tap I draw about 200ml. If there are any obvious lumps or particulate matter, stir until it is all fully dissolved. Then pour into your hydrometer tube and take your Original Gravity reading.

Another method I did try but it wasn't easy, was to use another vessel such as a large pot (i.e. larger than 10l) and add the water and then slowly add the ingredients stirring. I did find it helped to dissolve the dried ingredients have the water warmed up at low to medium temps, definitely not hotter than 50°C as it will cause clumping and possibly scorching or caramelizing the powder. And then once it is all dissolved and cooled down, take a sample to take your Original Gravity reading using a measuring cup/jar and then pour into your Droid and pitch the yeast.

Taking the Final Gravity reading is much easier. Just before kegging or bottling, I follow the @Captain 3 Droids  and @Dustin Frothman methods to let out about 250-300ml out of the Droid using the tap. This does two things, helps to clear the tap opening from any trub and/or hop matter and also allows you to look at and taste your final product. I let that sample settle as it tends to come out quite cloudy and also lets it come up in temperature. Once it has settled, I pour the resulting beer into the hydrometer tube and take the FG.

If using wort from all grain or a kit, then taking the Original Gravity is so much easier as you can just take the measure either before filling the Droid or after filling the Droid and then take the measurement before pitching your yeast.

To address one part of your question, I would never take the lid off for a gravity reading or anything else if you can help it. By opening your lid you expose your beer to all sorts of nasty stuff in the air. The only time this can't be helped is when dry hopping and by then its far to late to take an OG reading. Always use the tap to take samples.

For reference, one of the best websites for Homebrew calculators can be found here...
https://www.morebeer.com/articles/Brewing_Calculators

I hope this helps.

Cheers

Edited June 27, 2023 by Wazza_wantsbeer

[Thagomizer]

On 24/06/2023 at 1:30 AM, Mark Gillman said:

I have just purchased a glass hydrometer from a home brew shop in Adelaide. Whats the best way of taking the first reading?

Iam thinking that I will wait till the propagation period is over...24 hours or so, then either:-

1. Take the lid off and after sterilizing the Hydrometer drop its into the brew before it kicks off.
2. Take a sample from the tap into the storage tube it came in, then take the reading.

Any thoughts

A common formula for ABV (in percent) that @Wazza_wantsbeer alluded to is (OG-FG)*131.25.  If you are using only BrewArt elements and enhancers, just add up the integer number of packets and add 0.5.

I use a Tilt 2 Bluetooth hydrometer that allows me to get an SG reading without withdrawing a sample.  The (sterilized) Tilt device is the first thing put into the filtered water, before the packets are added.  However, the readings are not meaningful until the clumps of powdered malt dissolve, a few days after starting.  This means that the initial Tilt readings are not reliable, but the FG is fairly good.  

If you have an all-liquid wort at the beginning, you can use a refractometer to measure OG.  The advantage being that only a drop of wort is needed to take the reading.  However, the refractometer is not useful for finding the FG.

I would recommend taking an OG reading (Tilt device or drawing a sample for your hydrometer) as soon as there are no more large clumps as seen through the inspection glass or your droid tells you that fermentation has commenced.  I think this will under-read the correct value; but compare your results with adding up the packets and adding 0.5.

Happy brewing.