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-   -   Under-Carbonation Problem! (http://www.homebrewtalk.com/f13/under-carbonation-problem-151854/)

paint_it_black 12-14-2009 03:29 AM

Under-Carbonation Problem!
I've been brewing for a few years now... Recently relocated to my hometown and have been brewing with my dad (who has been brewing for the same amount of time as me). It seems that all of the batches we have churned out have been very undercarbonated. We use the standard 3/4 cup dextrose per 5 gal batch, but it just doesn't seem to do it. Most of our beers are practically still flat after three weeks. If given a month or two, they will pour with a slight amount of head, only if poured straight down the glass (not tilted). None of these are particularly "big" beers", though a couple have bridged up to the 6-7% ABV range. Still, even the lighter-on-alcohol ones have this undercarbonation issue.
Since we started brewing together recently, we've moved up to all-grain -- I'm not sure if that has anything to do with it. Since we have usually been hitting our target original gravities, I don't think that would be it, since we're acheiving the expected starch conversion, yielding a sufficient quantity of fermentables. (Dad says he's always had this issue, even with extract brews. Although I have had some of his beers that at least have beeter carbonation than those we've made of late)

We use tap water (Brita filtered), and don't know it's specific characteristics, but guys at the LBHS say they use their tap water and don't have this problem. So I don't know whether it could be our water...

Can anyone lend any suggestions as to why we're having this issue and how to fix it?

TheFlatline 12-14-2009 04:30 AM

I've been having a similar problem lately, but I think for me it's a temperature thing.

Things to try:

Grab a copy of brewsmith or use an online calculator to actually calculate the amount of sugar you need vs the temperature of your beer at bottling (which will make a difference. 50 degree beer and 70 degree beer use like an ounce of dextrose difference).

Keep your beer in a slightly warmer place. It may be too cold (my problem now) and the yeast is sluggish.

After a few days swirl up the yeast at the bottom of the bottle and get it suspended again. This usually really helps.

Use a different bottle capper. You might not be capping very well and you might have a slow leak on your bottlecaps.

I don't think tap water would matter if you are getting actual fermentation and hitting your FG.

paint_it_black 12-14-2009 05:16 AM

Thanks! Definitely gonna try the swirling technique right now.

rocketman768 12-16-2009 01:18 AM

Volume is a bad way to measure priming sugar. Measure by mass with a scale, and see this priming chart.


mithion 12-16-2009 04:03 AM

You say your beers aren't that strong but I've had 4% beers take 3 weeks to carb up nicely. For 6-7%, it may take a month. Besides time, we can definitely eliminate the obvious. First, the amount of priming sugar you use is fine. 3/4 cups is a pretty standard amount and I've had beers carb up fine using only 1/2 cups. Second, you say your beers are under carbonated but they still have some carbonation. That tells me you still have yeast in there so your problem is not lack of yeast. Now you didn't mention any consistency problems so I assume all your beers are turning out with the same carbonation. We can thus eliminate under mixing of the priming sugar. So we can eliminate those three issues.

With that in mind, I'm leaning towards temperature as being the culprit. When you're carbing your beers, you shouldn't have your beers sit below 60F for any significant time period. Below that temperature, most ale yeasts become very sluggish and a few strands will simply rapidly flocculate and drop to the bottom. Swirl your bottles and warm em up as suggested.

Lastly, just wanted to mention that head is not necessarily an indicator of carbonation. It's true you need carbonation to have head, but you can have beers with no head with good carbonation. If you want to have bit more head, a few things will help. The addition of some crystal malts, maybe some malted wheat, flaked oats or flaked barley will all help to have better head. :ban:

paint_it_black 12-16-2009 08:00 AM

Wow, thanks so much for the detailed reply. After reading it, I do think temp might have soemthing to do with it, but I'm pretty sure the temp in my beer closet rarely drops below the low 60s. I'm starting to really think maybe it's just time. I just cracked a Pumpkin Ale I bottled on 10/25, which didn't seem all too carbonated last time I tried it a few ago, but now is perfect.
Gonna keep swirling the more-newly-bottled beers every couple of days, monitor the temperature, and give more time :)

tkone 12-16-2009 03:40 PM

also, it REALLY helps to weigh the sugar rather than measure it -- and to vary the amount of sugar you're using depending on the carbonation levels you're looking for.

there are a slew of calculators on the internet that'll show you exactly how much sugar you'll need to achieve a certain volume of carbonation.

and yes, rousing the yeast can help if it's cooler where you're conditioning.

Matt Up North 12-16-2009 07:54 PM

My trick is to take equal parts sugar and water (so 6oz sugar and 6oz water) and put into a pyrex measuring cup and stick in the microwave for a minute on high and then stir, back in for a minute and then stir, doing this until all of the sugar is dissolved, about 3-5 times. Then I pour that into the bottling bucket, which is room temp, and siphon the beer onto that. Then stir the hell out of it (since the oxygen will be consumed by the yeast anyways). Bottle and then leave as close to 70* as possible for two weeks and then enjoy. Any cooler and it takes longer. My latest was carbed at 2 and I started drinking at 3 weeks.

Also, if you leave your beer too long in primary, be sure to take up a little yeast so that the beer can carb. It sounds like you have enough yeast though, so disregarrd this step.

paint_it_black 12-16-2009 08:12 PM

I'll definitely be using a calculator (such as the one linked above) and weighing my sugar henceforth. I'm going to do that today, actually, as I'm about to bottle my Aberdeen (Newcastle clone). Thanks for all the input guys! I'll keep ya posted on my findings.

maltbarleyhops 12-17-2009 07:23 AM

definately weigh your corn sugar. it has such a high compaction rate. a few taps on the table with the measuring cup and a cup becomes 3/4.

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