View Full Version : Problem with degassing and Carbon Dioxide

04-17-2015, 02:36 PM
So here is my story...

I made a two gallon batch of must by adding 3kg of clover honey and 2lbs of pureed blueberries (using the 1lb of fruit per gallon rule of thumb for a light flavor). I added water till just over the two gallon line in my three gallon bucket and used the nutrient instructions from the Bray's One Month Mead. The pH level just below neutral at 6.8 and had a SG of 1.118. I pitched a packet of Lalvin EC-1118 into the must and within an hour it was churning away live you would not believe.

I was keeping track of the SG to use the staggered nutrition that is recommended in the BOMM recipe and the hydrometer was dropping like a stone. It was incredible, the must finished with a SG of 1.000 in seven days!

I gently stirred the must to get rid of the carbon dioxide and then transferred the by siphon to two single gallon jugs. The siphon was filtered using a muslin bag so the pulp was left behind. I screwed caps on the jugs and put them in a cold room to settle.

Here is where things get interesting... I check on the mead a couple days later to see if the lees are settling and they are but there is a sound of escaping gas coming from both the jugs. I slowly unscrew one the the jugs and it almost erupted on me like some soda vinegar volcano experiment! Only by the grace of my super human reflexes do I manage to cap it down just in time to not lose any of the mead. I try to very slowly loosen the cap again and I manage to find the sweet spot between foaming and gas escaping that keeps it from overflowing.

This seems like an incredible amount of Carbon Dioxide being released, it lifted the lees off the bottom and started to swirl them around on its own. Is it possible that the mead is still fermenting? It is in a cold dark cellar at about 10 degrees Celsius and like I said the SG reads 1.000 (it also tasted dry). How do I degas this batch without loosing mead in an eruption?

04-17-2015, 04:09 PM
Do you have a solid stopper/cap on those? Being so young (and still full of CO2), they should really be under a filled airlock. I typically keep an airlock in my fermenters until I'm ready to bottle.

Also remember that 1.000 is not technically completely dry. Alcohol is less dense than water, so batches routinely hit the 0.990 - 0.999 range (especially with a beast of a yeast like EC-1118 ). 10C is also still within Lalvin's posted temperature range for EC-1118 (10C - 30C), so it's entirely possible that it is still chewing through what little there is left of that sugar.

Medsen Fey
04-17-2015, 05:07 PM
Your mead is probably still fermenting. I'd get it back under airlock.


04-17-2015, 06:27 PM
I put the brew back in the bucket and airlock'ed it. But now I am curious; why keep the airlock on till bottling? As I understand the air lock is there so there is no hard seal and risk of a pressure explosion while keeping airborne contaminants out by pressure differential/water trap. If there is no more gas being generated why bother with an air lock and not just put on a cap on it for ageing?

Chevette Girl
04-17-2015, 06:51 PM
It can take a while for degasing to happen naturally, but if it's that exciting it's probably still fermenting and as valverij said, it can keep going below 1.000. Typically you'll want to leave the airlocks on in secondary until you're sure there's no activity and the SG has stopped dropping. It allows the trapped CO2 to escape (one thorough degassing isn't going to do it) and also allows for continuied fermentation which is quite common in secondary, at least for the first few weeks.

I tend to leave my brews airlocked until bottling, sometimes for years, because I don't often stabilize my meads and some of them still have residual sugar, so in theory the yeast could wake up and get back to work at any time and I would rather risk spoiling a mead by forgetting to fill an airlock than making a 1-, 3- or 5- gallon bottle bomb in my house.