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Recently I tried my first mongrel brew, made with left over yeast and hops from past adventures. I also bought 1kg of Malt and decided to add 250gm (as according to my hydro my alc. was a tad low in the past) of dex to a BR I.P.A kit. and fill to 22L. Having waited a while (maybe where my problem lies) in vain for the the temp to drop I took and SG reading and pitched anyway at 26C. According to my hydro the SG was 1068- I seemed to have solved my alcohol problem ( I wish I could say that for real!). I have read posts about variability of hydromter readings and was wondering how useful these things are? The liquourcfraft calculator says I should have a OG of 1046 and an FG of 1011 giving me 5.4%. How realiable a method is measuring the fermentables and final volume for determining alcohol percentage? Does anything affect this equation, such as temp. of fermentation, amount of added yeast, water quality, or will X+Y always equal Z? Having said all that I am not super fussed, all the beer tastes good and gives me a pleasant sense of well-being. It just seems a waste of time and beer doing hydro tests (except to determine end of ferment.) if the other method will do. Any thoughts?

The things that affect alco%, are the yeast you use, the ammount and type of fermentables, the total volume of wort, and how far you allow fermentation to go (ie- racking often will increase alco%).

It just seems a waste of time and beer doing hydro tests (except to determine end of ferment.)

I prefer to not waste beer doing tests. I leave the hydrometer in the fermenter and read it from time to time to determine changes. I usually just give it a spin to remove anything that is clinging to the sides.

The ABV of your beer is easily determined. You start with a mixture of sugars and water and you use a hyrdrometer to take the Specific Gravity.. remembering that your hydrometer is temperature speccific, thus if your hyrometer is calibrated at 15C and your wort is 26C then the specific gravity is actually higher than your hydrometer reads (I can give you the correction formula if you wish). The fermetable sugars are then by a series of conversions converted into ethanol and a lot of by products, ethanol is oabout 70% the gravity of water so even at 5% ABV it makes a difference. There is avery simple formula that I can send which takes the lower gravity of ethanol into account and wil allow you to pick your ABV.
Rule of thumb though, with a reasonable attenuation 1040 SG will give you 4%, 1050 just under 5%, 1060 5.5%, 1070 6% to 1120 about 9-10%

Kurtz

Clintsc9 wrote:

It just seems a waste of time and beer doing hydro tests (except to determine end of ferment.)

I prefer to not waste beer doing tests. I leave the hydrometer in the fermenter and read it from time to time to determine changes. I usually just give it a spin to remove anything that is clinging to the sides.

I have often wondered about this
are there any problems with leaving the hydrometer in the fermenter
do others do this

yeh dags !!
good comment
I actually found a still working and still accurate digital thermometer in the bottom of a fermentor once...true !!!

Kurtz

Dags,

From a food safety point of view you shouldn't put anything glass into your beer (I am assuming you have a glass hydrometer). If it breaks you have lost all that beer. That is why you thief a sample and take the measurement in a test jar.

Dogger

I must add the only reason i take a reading is to samble my brews along the way. Havent run outa beer doing this yet always enough for the keg and less to bottle.

Thanks all for your replies. Just a few further queries if you wouldn't mind.
Does the type of yeast only or also the amount of yeast (obviously up to a point) affect the ABV? Also, why was my OG reading so high? I have made (an admittedly low) number of brews with 1kg brew enhancer and struggled to get an OG of 1040. All I thought I was effectively doing was adding 250-500g (whatever the blend is?) more malt, other posts talk about adding a kilo of dex to boost alcohol? I gave the ingredients a good mix in a bucket before adding them to some cold water in my fermenter and then filled. Probably could have splashed it up a bit more... Is this distortiing my reading?I did wait a while before testing.
Kurtz, apparently my hydrometer is callibrated at 20C if the reading is higher at higher temps it's gonna be a hot time in the old town the night I open a bottle. I don't think I did anything, besides add 250g more ferementables, differently, so why the high reading? Cheers in advance.

Cheeno,

The amount of yeast you add should not affect alcohol content, as the yeast multiplies in the fermenter anyway. However, pitching more yeast than less is a good idea as it gets the fermentation off to a good start, helping to avoid infection.

Adding 1kg of solids to your beer will definitely increase the original gravity. 1040 certainly sounds about right for the ingredients. However, depending on the makeup of this (i.e. more malt, less glucose, etc) the final gravity will be higher or lower because different ingredients ferment out more fully than others.

Cheers,

Oliver

Ta muchly oh great one. The next brew, a simple HBS clone, seems to be much more within the realm of possibilities. Although, after adding just (approx) 100g honey to 1kg BE I got an an OG of 1050 (don't know how I do it?) but that seems a bit more reasonable. Just racked into secondary after five days and she's 1014 and still bubbling.

Love the site, it's not just grouse...it's grousey grouse!

kurtz wrote:your hyrometer is calibrated at 15C

How is this measure or monitored?

Capt'n,

Your hydrometer should have what temperature it is calibrated at printed on the paper inside the tube. Mine came with a printed sheet covering details like correction for temperatures etc.

Cheers,
Greg.

gregb wrote:Capt'n,

Your hydrometer should have what temperature it is calibrated at printed on the paper inside the tube. Mine came with a printed sheet covering details like correction for temperatures etc.

Cheers,
Greg.

Ok thanks for that greg...greatly appreciated!

JaCk_SpArRoW wrote:

kurtz wrote:your hyrometer is calibrated at 15C

How is this measure or monitored?

If I'm not mistaken, most hydrometers are calibrated to 20C.

Below is a correction table taken from this thread - http://www.homebrewandbeer.com/forum/vi ... .php?t=574 - for a hydrometer calibrated to 20C.

Code: Select all

Temp(C) Correction
4-10       -2
11-17      -1
18-22      0
23-26      +1
27-29      +2
30-32      +3
33-35      +4
36-38      +5
49-41      +6

So let's say that your wort was 27C when you took the reading of 1035/36. Therefore, the corrected reading is 1037/38.

Cheers,

Oliver

Thanks Olly, I'll read the info that came with my hydrometer!