Why brewing out so FAST!!??

[keelbolt]

All Grain. Normally, my brews take about a week or so to brew out. Friday, I brewed two 19Litre batches of a dark ale. By Saturday morning, both were going like a train on speed. Today, they've slowed right down, and it seems that they are brewing out VERY quickly.

Admittedly, I changed the water chemistry a bit - lowering the ph - and added some yeast food to the final minutes of the boil. But I'm curious as to WHY the beer is fermenting so very quickly. Is it a sign of a weak beer, poor taste, or what?

[Piscator]

What temperature are you fermenting at - do you have temperature control?

What yeast are you using?

Are you harvesting and re-pitching or growing a starter?

Is your comment based on observing the yeast krausen visually or measured gravity readings?

[keelbolt]

Room temperature of my garage.
Nottingham in one and safale 04 in two
Pitched new from dried yeast
Observation of rate of gas escaping from airlock

Thanks for questions

[boingy]

Measuring the gravity is the only reliable way to tell how it's doing. Airlock bubbles are a very unreliable way.
Both those yeasts are fast workers so given perfect conditions they will do most of the biz in a few days then take a few more to finish off.

[Piscator]

Measuring the gravity is the only reliable way to tell how it's doing. Airlock bubbles are a very unreliable way.
Both those yeasts are fast workers so given perfect conditions they will do most of the biz in a few days then take a few more to finish off.

You beat me to it Warmer weather will speed things up without a brewfridge that's for sure and Notty and S04 are both quick workers.
The bulk of the sugar conversion can be over in a few days as said - but that is not the same as the fermentation being completed. The yeasties will need longer to finish working on the various by-products they made earlier on - this will improve the taste of the beer, so don't be tempted to move it off the yeast too quickly.

Gravity is the only real way to know what is going on. One side effect of a racing fermentation might be fusel alcohols that can give you a raging headache.

Do you have a min/max thermometer you can use to establish what temperatures the brews are exposed to? Room temperature in a lot of places lately will have been 25C or more - the yeast can generate a couple of degrees itself on top of that, so it could have been a tad warm.

[Rick_UK]

Yes the warmer the yeast the quicker it works. I'd be a bit worried it was getting too warm if it's really rapid (under 3 days) which will produce off flavours. Remember your beer will be a few degrees above ambient while it's fermenting. If you dont have a brew fridge you can cool it down by wrapping it in wet towels with a fan blowing on it for the warmest hours of the day.

I don't have a fridge but find it rarely gets above 20 in my garage. If it does I use the wet towels and fan trick to good effect with an aquarium heater to keep it at @20 when the ambient temp drops below this.

Controlled fermentation temperate is one of the best improvements you can make to your homebrew set up IMHO.

Rick