Continuously brewing low ABV

[fursey]

Hi all,
I'm extremely new to home brewing but so far every brew I've made seems to have a very low ABV, even a Bock beer which only had an approximate ABV 2.2%. Whilst I'm not expecting to brew strong beer especially from kits, I was hoping to brew beer around the 4.5% mark.

I have a feeling my first brew (the bock) was at too high temperature when I pitched the yeast, but I have been more cautious on subsequent brews but to no avail with the ABV.

Current brew temperatures have been circa 22C, could this be a possible cause?

Any advice would be greatly appreciated.

Thanks

 

[homebrewdad]

How are you measuring your ABV? If you are following directions, hitting volumes, etc... there is no way your ABV is that low.

To get your ABV, you need to take a gravity reading (with your hydrometer) before pitching your yeast (AKA your OG reading). Use the SG scale, *not* the ABV scale - that is used for wine, not beer.

When fermentation is done, take a new reading (aka FG).

Subtract FG from OG and multiply by ~131. This gives a close approvimation of ABV.

Example: you brew a 1.052 OG beer. It ferments down to 1.013. Your ABV is ~5.11%.

 

[Revvy]

Also, realize that if you are brewing with extract and topping off, your initial gravity reading may be wrong. Read this for an explanation of why, and go by what the gravity reading in the recipe says it should be. And then follow homebrewdad's excellent info.

 

[fursey]

My OG was 1.038, FG was 1.02. Final gravity was constant for 2 days

 

[homebrewdad]

My OG was 1.038, FG was 1.02. Final gravity was constant for 2 days

Revvy of course is right. Did you use top off water when you brewed? If so, what was your recipe's target OG?

 

[fursey]

Stated OG was 1.047. I did use topping off water and this certainly seems to be a logical reason. It doesn't seem very strong though and is very sweet.

 

[homebrewdad]

It's not surprising that it is sweet at 1.020 - that is a fairly high FG. And it still wouldn't be strong, using your target OG... that's about 3.54% ABV.
I'm betting the target FG was probably more like 1.013 or 1.012, which would put you in the 4.5% range.

22 degrees C is just under 72 degrees F, so your yeast shouldn't have stalled. You might get some warm fermenation byproducts (esters, maybe fusels), but I do hate it for you that fermentation has stalled.

You are sure gravity is stable, right?

 

[fursey]

I measured the same over 2 days and the day prior I recorded 1.022 so I assumed it had reached steady state, perhaps it had just slowed and I should have left it for a few days longer.

 

[bk0]

At this point you should be leaving your brews alone for at least a week. Measure OG, pitch yeast, seal up the container and leave it alone for at least 7 days.

At that point if your FG is still high my guess is you have a yeast health issue, or you're underpitching.

 

[homebrewdad]

At this point you should be leaving your brews alone for at least a week. Measure OG, pitch yeast, seal up the container and leave it alone for at least 7 days.

At that point if your FG is still high my guess is you have a yeast health issue, or you're underpitching.

This. Do note that if you don't have steady gravity readings for three days, you shouldn't assume the beer is done - that's a great way to get bottle bombs.

Also note that many of the vets here advocate leaving the beer alone for two (if not three) weeks.

 

[fursey]

I suppose the morals he story is patience is a virtue. I guess I was maybe too keen to get my first brew kegged.

I'll wait longer from now on and see how I go. Thanks for the advice, very much appreciated.

 

[homebrewdad]

I suppose the morals he story is patience is a virtue. I guess I was maybe too keen to get my first brew kegged.

I'll wait longer from now on and see how I go. Thanks for the advice, very much appreciated.

Of all the skills you can learn as a new brewer, patience is perhaps the most important. Good beer often just takes some time. Sometimes, a lot of time.

 

[gmcastil]

Also note that many of the vets here advocate leaving the beer alone for two (if not three) weeks.

At minimum. With the exception of dry-hopped IPAs with a lot of hops, mine don't leave the fermenter for at least a month.

 

[fursey]

Do you take hydrometer readings during that time

 

[dfc]

At minimum. With the exception of dry-hopped IPAs with a lot of hops, mine don't leave the fermenter for at least a month.

I just bottled an Imperial Stout that sat on the yeast for 2 months.

 

[bk0]

Do you take hydrometer readings during that time

There's no point. For most brewing you only ever need to take two readings: OG and FG. (If you start doing things like adding fruit or other fermentables in secondary then it's a different story)

 

[homebeerbrewer]

How long has it been fermenting?

 

[gmcastil]

How long has it been fermenting?

There are different phases of fermentation:

http://www.whitelabs.com/beer/Yeast_Life_Cycle.pdf

The length of time that actual fermentation is going on depends upon several factors, such as yeast strain, wort gravity, temperature, amount of initial oxygenation, yeast health, available nutrient, etc. By leaving the beer in the fermenter for a month or so, more of the things in suspension drop out. In other words, over time, the beer clears.

Many homebrewers advocate racking from one fermenter into other, which is usually referred to as a secondary fermentation. If done after fermentation is actually complete, this isn't really a secondary fermentation at all - it's just letting it sit longer and letting more things drop out of suspension. Others will recommend dropping the temperature down very low (cold crashing) in order to accomplish the same thing.

There is a lot of evidence which suggests that these practices are not really necessary and that one can leave the beer on the yeast for much longer periods of time and ultimately achieve the same or better results. I personally choose to forgo these additional steps and leave my beers in the fermenter for a month and undisturbed, so I don't do gravity readings at all. In fact, the only time I take gravity readings at all is pre-boil. If my gravity is a bit high or low, I'll either bump it up with some DME or adjust my hop additions accordingly. If I had a refractometer or something that let me measure my gravity without having to break out the wine thief or anything like that, I might measure it post-boil and prior to bottling.

I don't really get too carried away with trying to know what my gravity is on a day-to-day basis. There are far more important things to obsess about than the gravity in my beer. It amazes me how many homebrewers ignore yeast pitching rates and fermentation temps. Believe me, those have a lot more to do with the quality of your finished product than whether or not it took you 7 or 10 days to hit terminal gravity.