View Full Version : Dissolved C02 In The Mead

05-15-2013, 04:44 AM
Hello everyone,

I am a beginner. Here is my very early experiences.

1st batch was just traditional mead with raisins, it was unsuccessfull, i faced and ended it up after 40 days and there was sock smell :) I think it is because of the raisins which i bought from an open air local market.

2nd batch is traditional mead. It has been 1 week since i racked it after 30 days of fermentation. It is still very slowly fermenting. I am waiting some bentonite to try to clear and bottle it after 2 months will be completed. It tastes totally diffrent and better then 1st one.

3rd batch is apple cinnamon mead with my own methods. It is fermenting very good for 6 days.

I use flower honey, i use bakers yeast, i use the basic recipe calculations on this site.

I am using silicone air hoses for air lock, i am using hot glue gun for sealing everything.

I have a result about the dissolved CO2 in the mead after these small experiments :
When a used a small diameter and long hose (between the cork and the jar). After i noticed there were a lot of dissolved CO2 in the mead. The inner diameter of the hose was 4mm.

In second batch i used 10mm diameter very short hose and there was more more less dissolved CO2 in the mead.

I think is it about the pressure resistance of your CO2 release system. Because if CO2 has a resistance for releasing there will be gas pressure in your fermenter. Under that pressure CO2 will dissolve in your mead. And may be it will take time to get clear.

I would like to learn what do you think ?

By the way everybody says that 30 seconds one bubble or something to understand that first fermentation is over, but it is again all about your batch volume and CO2 release diameter.

All the best...

05-15-2013, 06:17 AM
The two things that affect dissolved CO2 the most are pressure and temperature. At near freezing temperatures water can hold somewhere around 3.4 g CO2 per liter of water. At 10C/60F that goes down to about 2.4g/l, and at 20C/78F that goes down even further to 1.7g/l. The affect of pressure can be large as well when the pressure difference is large, but with your setup it sounds like there isn't a pressure difference to speak of between the two cases. For the temperature and pressure ranges we deal with in fermenting, dissolved CO2 scales roughly linearly with pressure. So a difference between 1 atmosphere and 1.1 atmosphere will correspond at 0C to a difference between around 3.4 g/l and about 3.7 g/l. The chances of your having that large of a difference in pressure, however, is very low. Your differences are probably on the order of 0.01 atmospheres, making for at most a 1% difference in dissolved CO2 attributable to pressure.

Put differently, the pressure difference in your setup will yield less of a difference in dissolved CO2 than a 1 degree temperature difference.

One other thing that could affect your results would be the degree to which the CO2 mixes with the atmosphere. If your tubes are open to the air then there will be a fairly big difference there: the short, wide tube will allow a lot more mixing than the long narrow tube. This will make the partial pressure of CO2 much higher with the long narrow tube than with the short wide tube, leading to more dissolved CO2 in the former case. If the free ends of the tubes are under (preferably sanitized) water, however, mixing won't be an issue -- both setups should end up with just CO2 and water vapor in your fermentor, yielding the same approximate levels of dissolved CO2.

Perhaps a bit overkill on the explanation there, but I hope it helps.

05-15-2013, 07:50 AM
Thanks for the reply. It helped to understand a little bit more.

I thought pressure difference was more then 0.01 bar but now i calculated, it is approximately the same. You say this kind of pressure difference doesn`t make any sensible effects.

Also my tubes are finishing in the water.

So the last difference between two batches was racking them with different diameter hoses, may be bigger diameter was helpful to release more dissolved CO2 from the mead.

05-15-2013, 08:37 AM
Can't say anything about the effect of hose diameter on CO2 coming out of solution, but there is one other thing worth considering. If while racking the temperature of the liquid goes up, CO2 will come out of the liquid. If the temperature of the liquid goes down it probably won't. So, for example, if you rack a 20C mead when the ambient temperature is 25 you might expect a small amount of warming leading to more foaming, while if you rack that same mead when the ambient temperature is 15C you would expect less foaming. This is especially true of the first bit of the mead into the container -- a container full of mead changes temperature slowly, but an empty container is likely to be at ambient temperature itself and lead to a sudden temperature change for the first bit of mead to go into it.

Either that or the diameter and length of the tubes is actually making a difference. My first thought is to eliminate the known variables first, though.

Out of curiosity, were you pushing the mead out of the original container with pressure or just using the siphon to draw the mead out? If the former, then a long thin tube would make for less foaming just as it does for dispensing beer being pushed out of a keg under pressure. If the latter, I don't know if it would make a difference.

05-15-2013, 09:00 AM
I am racking the mead in the same room where they are waiting. Temperature is not changing too.

I am just siphoning without pressurizing the fermenter.

And according to you what would be the negative or possitive effects od dissolved CO2 in the mead. I think it will get clear faster if there is less dissolved CO2, thats why i am curios about it. And i will watch my second batch when it is two months old, if there is some notable difference with first one, we can talk about the results again if you like. Also 3rd batch seems to ferment faster with large diameter hose CO2 releasing. I am watching it too.