Fermentation activity level

Has anyone observed their primary fermentation in terms of activity level such as bubles per minute at different intervals? Number of bubles/minute vs time chart. I cannot help it but keep chceking my first and curious becasue I don't know what to expect.
My IPA was pitched at 70F in a carboy, placed in a room at 67F, carboy temperature went up to 74F and stayed like that. Started bubling in four hours with almost 140-150 bubles/minute. 24 hours later, temperature is dropping and bubles are 7/minute. It looks like pretty drastic change. Is it normal, I wonder...

It sounds normal to me.Some yeasts take off like gang busters and the slow down drematically. Others are slow starters and seem to just plod along. That's my 2 cencts worth.

It does not sound abnormal. Relax and let it ferment for a week at the lower temperature. Mine usually go strong for a day or two and then just plod along for the rest of the week. I believe that the temps in the 60's will produce a better tasting beer.

The basic shape of the curve will always be the same: a relatively fast ramp up in rate, followed by a slow decay to "I'm racking it.". Relatively fast is 2-48 hours. The slow decay can be months for meads & barleywines, but is normally 3-10 days.

If you pitch a high gravity ale on the cake from a previous batch, the lid can blow off the fermenter in 30 minutes or less.

TekelBira said:

My IPA was pitched at 70F in a carboy, placed in a room at 67F, carboy temperature went up to 74F and stayed like that. Started bubling in four hours with almost 140-150 bubles/minute. 24 hours later, temperature is dropping and bubles are 7/minute. It looks like pretty drastic change. Is it normal, I wonder...

Click to expand...

If it went that flat out at the start, then it is probably pretty much done already. There is always an extended period of much slower fermentation following the initial 'burst'.

If you intend to secondary, leave it a few more days (the bubbling will continue to slow) before racking. If you are just doing a single stage fermentation, give it another week or so and then bottle. All will be well...

Thank you all. It is comforting to know that I can get the most needed help/info here in a pinch. I am going to rack it into the secondary perhaps by tomorrow as it looks two bubles a minute this morning.
Cheers...