The following days i monitored the fermentation progress by measuring SG, pH and temperature.
Whenever the temperature increased to just above 24.0C I added ice-cubes to a cooler and let the cooling system of the fermenter bring the temperature down - usually to around 18C within half an hour. The ice was then melted and I just stopped the flow.
pH was measured to ensure that it would drop due to the generation of CO2 by the yeast, and that pH would not drop so low that the yeast was knocked out. When the fermentation was over pH was measured and I will than later have to adjust pH to just below 4 to stabilize the mead.
SG was measured to follow the conversion of sugars and this time I used staggered nutrition addition SNA to ensure that the yeast had the best conditions untill the alcohol limit of the yeast had been reached. The initial gravity, OG, was 1.116. The yeast can tolerate 15% so from experience, I should get about 14% alcohol for a drop in gravity of 0.100 or 100 Oe, so 15% would be about 107 Oe. So for a 100% conversion my gravity should drop from 1.116 (100%) to 1.009 (0%). The results are plotted below.
As can be seen from the graph I have full conversion - actually a bit more - and the fermentation is almost complete after 10 days. There are also no sudden premature change of fermentation rate which is typically due the lack of nutrients. All in all an almost perfect fermentation :o)
Details from the log are found below
Wednesday 14th of October
Temperature
23.9C - OK
OG 1.116
Starter
added in the morning at 8
Happy
bubbling in the evening
Thursday 15th of October
Evening
SG 1.110
Temperature
23.1C
1st nutrition addition
5g of
Fermaid K
16g of
Ammonium Carbonate (Hjortetaksalt)
4 g of
Potassium Carbonate (Pot Ash)
Make slurry
of all powder with 100 ml of water.
Add slowly
while stirring. Stir well when all is added and bubbling settles.
pH after
addition: 3.58 – OK
Taste nice,
smell a bit off
Saturday the 17th of October
Evening
SG 1.086
Temperature
23.1C
pH 3.52
before addition
2nd
nutrition addition
3g Fermaid
K
9g Ammonium
hydrogen carbonate (Hjortetaksalt)
4g
Potassium hydrogen carbonate (Pot Ash)
pH after
addition 3.64
Monday the 19th of October
Evening
SG 1.056
Temperature
23.4C
pH – not
measured before addition
3rd
nutrition addition
3g Fermaid
K
6g Ammonium
hydrogen carbonate (Hjortetaksalt)
4g
Potassium hydrogen carbonate (Pot Ash)
pH 3.86
after addition.
Tuesday the 20th of October
Evening
SG 1.040
Temperature
24.2C
pH 3.79
Cooled with
1 aliquot of ice
Wednesday 21st of October
Evening
SG 1.028
Temperature
22.5C
pH –
Friday 23rd of October¨
Evening
SG 1.014
Temperature
22.8C
pH –
Friday the
6th of November
SG = FG
=0.008
Remove
bottom yeast – waste 1 L
Temperature:
21.5C
pH: 4.01
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