Another Fermentation question

[Chris_S]

It is widely acknowledge that fermentation is usually finished after approx 14 days in the FV and/or the SG has stayed constant for consecutive days.

My Coopers Real Ale kit has been in the Fermzilla for 18 days under a very low pressure of about 2-3psi. I have not checked the SG yet, but it appears to be still producing CO2 at greatly reduced rate. This is evident when the spunding valve release pressure is increased to a much high value. The needle on the gauge still rises.

I plan to bottle this batch as it is for my fathers consumption.

So my question is, even after this length of time is it safe to attempt bottling now or leave it longer?

 

[Cheshire Cat]

You really need to ensure the FG is stable on or near the planned level before bottling.

 

[terrym]

You need to take an SG reading which will eliminate most of your uncertainty.

 

[Chris_S]

So I took a reading this morning coming out at 0.996

Am I right in thinking that Coopers kits rarely go below 1.008 , so what’s happening

 

[Leon103]

Is your hyrdometer correct. Have you tested in water. Did you test at the correct temperature and was the beer carbonated?

 

[Chris_S]

Is your hyrdometer correct. Have you tested in water. Did you test at the correct temperature and was the beer carbonated?

No carbonation, about 21c

 

[terrym]

So I took a reading this morning coming out at 0.996

Am I right in thinking that Coopers kits rarely go below 1.008 , so what’s happening

Yes, in my experience of brewing quite a number of Coopers kits, if done with their yeasts the FGs rarely goes below 1.008. My records show I made up this kit five times using the kit yeast with OGs in the range 1.043-1.046 and FGs in the range 1.008 - 1.012.
So if you have a reading of 0.996 its either a dodgy hydrometer or you have got a wild yeast in there which can, apparently, drive down the FG.
So dunk your hydrometer in clean water at about 20*C and it should read about 1.000. If its about that your problem may be an infection
Otherwise what does it taste like?

 

[Chris_S]

Yes, in my experience of brewing quite a number of Coopers kits, if done with their yeasts the FGs rarely goes below 1.008. My records show I made up this kit five times using the kit yeast with OGs in the range 1.043-1.046 and FGs in the range 1.008 - 1.012.
So if you have a reading of 0.996 its either a dodgy hydrometer or you have got a wild yeast in there which can, apparently, drive down the FG.
So dunk your hydrometer in clean water at about 20*C and it should read about 1.000. If its about that your problem may be an infection
Otherwise what does it taste like?

It tasted ok

Which way will the reading sway if hotter or colder?

 

[Chris_S]

Must be a dodgy hydrometer, just took another two samples, and both were within specified range. Strange.

 

[terrym]

It tasted ok

Which way will the reading sway if hotter or colder?

It only makes a point or two difference at the temperatures you are dealing with.
More here
https://www.brewersfriend.com/hydrometer-temp/

 

[Leon103]

No carbonation, about 21c

But you said you were fermenting under pressure so I would expect some co2 in the sample

 

[Chris_S]

But you said you were fermenting under pressure so I would expect some co2 in the sample

Yep, but a very low psi, wanted to keep the system closed but enough to enable samples to be drawn off without having to open the lid of the Fermzilla.

 

[Wynne]

An increase in temperature would cause the pressure in the fermenter to rise. You are better off relying on SG readings to determine whether fermentation is finished.

 

[Chris_S]

An increase in temperature would cause the pressure in the fermenter to rise. You are better off relying on SG readings to determine whether fermentation is finished.

Was talking about water or wort temp when checking the hydrometer.

 

[Wynne]

I think you may have misunderstood my point. I was commenting on your statement “but it appears to be still producing CO2 at greatly reduced rate. This is evident when the spunding valve release pressure is increased to a much high value. The needle on the gauge still rises”. The pressure increase you observed may have arisen from a change in ambient temperature rather than from continuing CO2 generation from fermentation. Hopefully, you are now getting consistent SG readings. Enjoy!