False sg readings on change of sugar

[Alky]

Hi forum, I have been brewing kit beers for many years mainly Youngs and Muntons 40 pint size and recently changed over to Youngs fine brewing sugar on a whim. This is the second brew with it that I have made.

I replaced the usual 1kg of white granular sugar weight for weight with the Youngs brewing sugar and for some reason the sg was only 1030. This went down to 1008 at finish which I calculate at well under 4%.

The latest brew is ready for the yeast.but with 1 kg of Youngs sugar in the reading is a ridiculous 1020.

Obviously this cannot be right. I have tested the hydrometer in water which reads spot on 0000 and tried another but the same silly reading exists in the brew.

All water is boiled. There is definitely no infections.

Can anyone guess at what is going on? Thanks

[Alky]

Sounds like a stuck fermentation.

Are you keeping the beer between 18-24 deg c?

If so, try rousing the yeast by gently stirring it back into suspension.

Thanks but the fermentation isn't even off the ground let alone stuck. I took the sg reading before adding the yeast. I have a suspicion it's a false reading but why?

Yes temp' is spot on at 24 degrees.

[Jim]

Well, household sugar has an extract potential of 37 (for 1lb per gallon). As brewing sugar has only 30, you're losing 2 or 3 degrees of gravity there.

A couple of questions:

Did you measure the gravity of the same kit when made with household sugar, and if so, what was it?

How do you measure the total volume of your final brew? That can make a difference to the gravity as well.

[Alky]

Well, household sugar has an extract potential of 37 (for 1lb per gallon). As brewing sugar has only 30, you're losing 2 or 3 degrees of gravity there.

A couple of questions:

Did you measure the gravity of the same kit when made with household sugar, and if so, what was it?

How do you measure the total volume of your final brew? That can make a difference to the gravity as well.

Thanks Jim, With household sugar I was seeing around 1035 sg. Not sure what you mean about 'total volume of final brew'. I just take a sample from the 5 Gallon brew bucket.

It also seems very strange that I got 2 readings from 2 brews with the brewing sugar. First was 1030 and second was 1020.

Do you think I'd be better off going back to household sugar?

[Jim]

Thanks Jim, With household sugar I was seeing around 1035 sg. Not sure what you mean about 'total volume of final brew'. I just take a sample from the 5 Gallon brew bucket.

It also seems very strange that I got 2 readings from 2 brews with the brewing sugar. First was 1030 and second was 1020.

Do you think I'd be better off going back to household sugar?

1kg of household sugar contributes about 16 points of gravity in 5 gallons, so that means in the kit that gave you 35 the extract gave 19 points. 1kg of brewing sugar would give only about 13 degrees, so you would expect the gravity with the kit and 1kg of brewing sugar to give 19+13 = 32, which is about what you got.

The 20 reading is a mystery, though. It seems as though either the kit was faulty or the brewing sugar added nothing to the gravity (you did remember to put it in, didn't you ).

Re going back to household sugar; don't do it. Just add more brewing sugar - 1.2kg ought to do it.

[Aleman]

Oc course it could be not mixed properly, give the wort a damned good stir.

[Alky]

Oc course it could be not mixed properly, give the wort a damned good stir.

Just checked again and had a good stir but still low so added an extra 300g of household sugar to bring it up to 1040 which should hopefully
give me around 5% (it's a Geordie Yorkshire Bitter not a Youngs but I suspect they are both pretty much the same from sg point of view before sugar is added).

Is there maybe a chart that I can work out how much to use to get it up to 1040 when replacing household sugar with brewing sugar?

While I'm on about false readings. Last night I got a commercial tin of John Smiths OB and took a reading from that and it was sky high! Around 1020. What is this all about?

Thanks again for help.

[Jim]

.........While I'm on about false readings. Last night I got a commercial tin of John Smiths OB and took a reading from that and it was sky high! Around 1020. What is this all about?

Thanks again for help.

Probably bubbles of CO2 clinging to the hydrometer and making it rise up further that it otherwise would.

[Jim]

.....Is there maybe a chart that I can work out how much to use to get it up to 1040 when replacing household sugar with brewing sugar?

Multiply the weight of household sugar by 37 and divide by 30 to get the equivalent weight of brewing sugar required.

[DEV]

Have tried the Geordie kits, Bitter, yorkshire bitter, Scotish export, Mild,
all made as per instructions on tin with 1kg of white sugar.
Yorkshire Bitter - start SG 1032, drop 28, Alc 3.75%
Mild - start SG 1032, drop 28, Alc 3.75%
Bitter - start SG 1034, drop 29, Alc 3.89%
Scotish export - start SG 1032, drop 27, Alc 3.62%
Bitter + geordie enhancer - start SG 1034, drop 28, Alc 3.75%

Start SG - finish SG = drop, divide by 7.45 = Alc% vol
Have brewed Mild an Bitter with Spray malts instead of sugar, start SGs were the same, but finish SG at 1010 on both giving less drop and Alc%,
the kits state that finish is about 1004-5 for sugar which has been correct with my results, but not sure about results with Spray malts.
cheers