Dissolved C02 in Primary an its affects

[gmc]

Hi all,

It seems recently that my brews have had a ton of dissolved C02 in them, even after sitting for 3 weeks in primary. I have just put dry hops in my current 3 week old batch and the airlock has picked up to bubbling every 2 seconds. I noticed a lot of bubbles coming off as well when I stuck the hydrometer in there. Presumably the nucleation point on those solids causes the release of the dissolved gas. My main questions are these;

1. Is all this dissolved gas affecting my hydrometer readings by making it more buoyant and read low. (I really hope it is because I have had some very dissappointing readings)
2. Is all the dissolved C02 throwing off my priming. I think I have had a few inconsistant carbonations batch to batch, even though I measure the sugar very accurately.
3. Does anyone use techniques to get rid of the dissolved C02 in the primary to avoid 1 and 2, assuming that those are actualy problems that occur. If so what techniques do you use?

I think I have also had syphoning problem with all this C02. I am sure a few of you can recognise the situation where your syphon and tube is solidly full of beer and then you end up with foamy bubbles in there that stop the flow. You have to pump it again and disturb the sediment and possibly aeriate the beer more than you would want.

Any help or discussion would be much appreciated

 

[moto748]

I haven't got answers, but I'll make a few observations.

Firstly; what makes you think your brews have more dissolved CO2 than other peoples'? CO2 is not very soluble. Have you noticed a change since you started dry-hopping (I've never dry-hopped myself, so can't comment on that)?

You can spin a hydrometer between your fingers to try to release clinging bubbles. But I doubt your readings are being seriously affected.

Clearly siphoning problems aren't going to help, but I would have thought any bubbles caused by aerating the beer are going to be air, not CO2.

 

[Hoppyland]

Well, I would expect that your finished beer would be fully saturated with CO₂, for its temperature. But not super-saturated after 3 weeks, such that putting a hydrometer in would cause a release of CO₂ gas, unless you fermented under pressure and then subsequently reduced the pressure to normal atmospheric.
My comments are a bit theoretical, since I would never normally leave a beer 3 weeks in primary.
The siphoning experience I totally get. Basically, your beer is fully saturated with CO₂ at a pressure of 1 atmosphere. Transferring it by siphoning means that you have 1 atmosphere of pressure, at the surface of the higher ("donor") vessel, plus the additional pressure developed by the "weight" of fluid between the upper and lower ends of the siphon tube.. The lower "donor" vessel therefore has a lower pressure at the end of the siphon tube (i.e. it sucks!). Since the solubility of CO₂ in water is pressure dependent, then this reduction in pressure will cause CO₂ to leave solution and become gaseous again, i.e. bubbles. Which will possibly knacker the siphon effect!
To my mind, this is an entirely good thing. When you first transfer your beer it contains zero O₂, loads of CO₂ and therefore minimises oxidation problems.
(Apologies to any physicists reading this - regrettably I'm a biologist, so a somewhat "soft" scientist!! )

 

[RoomWithABrew]

Couple of things spring to mind.

Hops will act as nucleation sites to make bubbles form, much like Mintoe in a coke bottle but to a lesser extent.
Second think is that hops do contain Diastase enzyme so this enzyme will break down some of the longer sugars and these are then able to be
metabolised by the yeast into alcohol and CO2.
This is the reason for hop creep. Big problem commercially for some.

Important to make sure hop material has all dropped before bottling otherwise it's like adding extra priming sugar.

Degassing not a good idea as likely to get oxidation as a side effect. Carbonation calculators should take account of residual CO2.

Cooling the beer prior to bottling will help to keep the CO2 in solution and bottling into cool bottles. I pressure ferment and counter pressure bottle
so want my final vol of CO2 at the end of ferment and clearing. But that's a different ball game.

 

[gmc]

Is the conscensous that the c02 isn't making much difference to the hydrometer readings? That's a shame because I think my current batch is going to be **** water. 1.036 OG to 1.012 so far after 3 weeks. Had to dump 500 grams of extra sugar in it to get it to 1.036. Was 1.030 out of the kit and no sugar was supposed to be required.

I think a failed £8 experiment on one of those cheap Morgans kits

 

[foxy]

Is the conscensous that the c02 isn't making much difference to the hydrometer readings? That's a shame because I think my current batch is going to be **** water. 1.036 OG to 1.012 so far after 3 weeks. Had to dump 500 grams of extra sugar in it to get it to 1.036. Was 1.030 out of the kit and no sugar was supposed to be required.

I think a failed £8 experiment on one of those cheap Morgans kits

Take out half a cup from the fermenter swill back an forth with another cup this will degas the sample to take a reading. Be sure there is no yeast in the sample that will have an effect on the reading also.Brewers Friend gives an expected co2 by temperature, if you are cold crashing the co2 will stay in the beer. As for the hops, think where sugar comes from. Plants convert sunlight to sugar keeping it simple. There have been numerous cases of commercial breweries having to recall beer rather than face a fine for giving out the wrong ABV. Hop creep.