How to deal with Evaporation from Fermenters

[thedidey]

Hey all. I live in Arizona and I've been getting what seems like a lot of evaporation in my primary and secondary fermenters.

I was wondering what your experiences are regarding this issue.

My observations: My 2nd to last batch (a porter) I lost ~0.5-0.75 gal (not including other losses), So I brought it back up to 5 gal. before bottling and ended up with a weak, light beer. I think I should have added less to account for hydrometer readings, etc.

My last batch (a stout) I again lost ~0.5-0.75 gal. I didn't bring it back up to 5 gal. and bottled as is, but my gravity actually went UP while in the secondary and the beer was very heavy.

Guesses as to what to do: Add water to achieve a gravity instead of a volume. Carefully measure how much volume I lose to racking and hydrometer readings and only add the amount I lose to evaporation back in before bottling.

Note: This is not a fermentation temp issue, the air here is just ridiculously dry.
So what do you all think?
Thanks.

 

[GilaMinumBeer]

Are you open fermenting?

If not, better seals should solve the evap issue. If the fermenter is sealed then you should only be losing airlock or blowoff water.

strange indeed.

 

[Brew-Happy]

What type of fermenters? Carboys have such as small surface area at the opening that your losses should be low. If it is an "open" bucket then I can see that.

How certain are you that your starting volume is 5gal? The reason I ask is that you say your beer is "watery" after addition which suggests that your volume might be lower than you expect. Just a thought.

One solution would be putting your fermenters in a deep rubbermaid tub with snapping lid. Then put your fermenters inside and but a couple gallons of water in the tub with the fermenters. With the lid on your humidity levels should be high enough to reduce your evaporation.

 

[Gremlyn]

If you're losing water, you're definitely losing ethanol as well. I don't think this is an evaporation issue UNLESS your fermenter isn't sealed properly. That's far too much liquid to be losing. Are you measuring the liquid you put into your fermenter? What temp are you measuring it at? Hot liquid fills more volume than cold liquid does.

 

[thedidey]

The fermenters are a 6-gallon ale pale, and a 5-gal glass carboy, and although I just bought a couple S-type airlocks, I've only used the Vinty style (3 piece).

Gila, you bring up and interesting point. I bet I'm losing more in the Pail with that seal than in the carboy. I didn't notice because the 2nd of the 2 batches was already in the secondary when I found this problem.

Happy, I thought the wateriness was because I replaced what evaporated AND what I used for hydro readings and racking loss. My thinking being that I lost water to evaporation and beer to readings but added only water.

 

[thedidey]

Gremlyn, I've only been measuring when I put everything into the primary and when I bottle. Now that I've noticed the problem I'm going to try to keep tabs on all loss with a batch I have in the primary currently.

Temps should be close to one another. I ferment at 65-70 (using a rubber maid with water and a shirt draped on the fermenter) and the house was at 75 give or take during the 2 batches.

 

[hopsoda]

someone is drinking it

 

[dontman]

I think I may be confused. As far as I can see the contents of a sealed carboy or even a pail should have no clue what the relative humidity of the air ouside of the vessel is. They are two entirely separate volumes and there should be no evaporation INTO THE OUTSIDE AIR. The onlyu transfer of any moistture from inside to outside would occur in the co2 offgas but the relative humidity outside the vessel would have no bearing whatsoever on the quantity of liquid evaporated. The total volume evaporated in that air would be determined by temperature not outside relative humidity.

Further, as someone mentioned before, if 3/4 gallon were indeed evaporated you would have alcohol free beer because the alcohol would largely evaporate before the water even started disappearing. This is the principal of how alcohol is distilled.

You are wrong. Your beer is not evaporating. Any difference in volume is solely due to brewhouse losses, or mismeasurement. Back to the drawing board on hunting down this culprit.

I'm betting Ambien drinking binges.

 

[phatuna]

Diddy, it is a practice of many including myself to shoot for 5.5 gallons going into primary. The reason is that we are loosing close to 0.5 gallons due to yeast cake (I think the tech. term is "trub loss"), racking from primary to secondary or bottling bucket you are gonna loose some, hydrometer readings you will loose a bit more, and the bottling process you will also loose a bit.

I do not think that evaporation is your problem, the variables in the above list are very common and can be accounted for by shooting for 5.5 into primary.

 

[thedidey]

Not the gentlest of creatures dontman but your reasoning is sound. I guess I thought I could lose water through the (likely) imperfect seal of the 2 fermenters, but you and Gremlyn are surely correct about the alcohol leaving before the water.

Thanks all. I guess I'll have to watch my waste more.

 

[dontman]

Not the gentlest of creatures dontman

Didn't mean it in a mean way. Sounded much more good natured in my head than it appeared in my post. I guess I should of put one or two of these -

 

[thedidey]

no worries. I didn't think it was mean, just to the point. Either way, you gave me the answer I needed, so thanks