Poor Attentuation

[MARMITE]

Made a Porter Og 1058 on 12th Sept and pitched with 1 sachet of Gervin Yeast at 3pm, which was prepared as per the instructions on the packet ( a little short according to Mr Malty). Initially very vigorous fermentation and by 14th Sept gravity down to 1028 but surface clear. The next day tried rousing gently in morning but no effect, so pitched a further sachet of Gervin at 3pm (again prepared as per instructions, except I didn't reaerate due to the gravity being 1028). Today the gravity still at 1028. tried rousing but still no activity.

The only thing I can think of that might give a clue is a mash temp of 67C which was checked with a laboratory thermometer which does read 2C low at boiling point but is the same reading as another thermometer at 20C.

As anyone got any ideas, other than to make a new brew mashing at say 65C so even if the thermometer is out a bit the mash temp shouldn't exceed 67C.

[Matt]

What fermentation temp have you got there Marmite?

Was the Gervin yeast old and/or how had you stored it (wasn't it discontinued last winter?)?

n.b. Member Lazlo also had problems with Gervin stalling recently

Did you aerate before the first pitch?

Matt

[mysterio]

The mash temp shouldn't cause such a high terminal gravity. Try making a starter with some yeast and pitch it when it's actively fermenting.

[MARMITE]

Thanks for the replies lads.

1. Fermentation temp 18 - 21C.
2, Yeast dated 02/10 and stored in fridge since delivery 1 mth ago.
3. Wort aerated before first pitch and went off like a train until it stopped dead at 10.28. In fact in went off that well I had to clean the over spill.
4. Mysterio - are you suggesting I pitch yet again because I have already pitched twice plus rousing two or three times but no joy. If so what yeast would you use? I have only got Safale 04 or Windsor left but I wouldn't have thought Windsor would do the job if Gervin won't.

[Matt]

What does a sample look and taste like M?

[MARMITE]

Hello Matt
Sample is clear and quite bitter(hops-3oz fuggles for 90 mins+.33oz last 15 mins).There is no obvious sweetness and gravity still at 1028.

[MartialAnt]

How well did you aerate it? I didnt aerate one of my latest brews & its stuck at 1012 where as all the AG brews ive made so far have finished at 1007 & 1008. I only realised that i hadnt whisked it once the yeast was pitched.

Got to blame it ALL on the drink.

[MARMITE]

Well aerated by dropping about 2 feet. Surely if my initial fermentation was very vigorous then the wort must have been adequately aerated and the yeast would have already gone to anaerobic respiration when the beer had got to 1028..By the way if you are hitting final gravities of about 1012 or thereabouts on an 1045 brew that's about spot on. If you sometimes get 1008 maybe you are using something like Nottingham which goes lower than other yeasts or used highfermentables inyour wort.r

[Matt]

Hello Matt
Sample is clear and quite bitter(hops-3oz fuggles for 90 mins+.33oz last 15 mins).There is no obvious sweetness and gravity still at 1028.

M, are you sure that your hydrometer hasn't gone out of whack and its really lower and finished?

[maxashton]

Seconded, could be a duff hydrometer. Try putting it in water at 20 degrees.

[MARMITE]

I tested the hydrometer against another one this afternoon and both were reading 1028 and also the OG per my refractometer and hydrometer were the same

.

[Matt]

i'd rack and pitch a starter then I reckon.
Matt

[hoppingMad]

Hello Matt
Sample is clear and quite bitter(hops-3oz fuggles for 90 mins+.33oz last 15 mins).There is no obvious sweetness and gravity still at 1028.

No obvious sweetness
at 1.028 there will be an obvious sweetness. Sounds wierd to me.