Aerate or pitch more yeast ?

[Steam]

I brewed two 5 gallon All grain beers this weekend :

18 may : OG 1.072 - Belgian Strong Ale Yeast WLP545 - Main hop citra leaf
19 may : OG 1.060 - Belgian Ale Yeast WLP550 - Main hop galaxy pellets

After 3 days and 5 hours the first beer is fermenting strong and still bubbling a lot , 1 bubble every 3 seconds .

After 2 days and 7 hours The second beer fermentation has slowed down considerably and the foam is all gone , 1 bubble every 17 seconds .

I kept the temperature at 78-80 . I wonder if there's a problem with the second beer . I only brewed 6 beer so far and i never experienced this , should i try to aerate it , shaking it or pitch more yeast ?

 

[WoodlandBrew]

Let it ride. If the yeast has mostly settled to the bottom you might consider giving it a swirl to get more back up into suspension, but I would not shake it or aerate after a few days of fermentation. The second beer was about 15% lower in starting gravity, and if there was equal or more yeast it would get though the short chain sugars faster.

If you would like I have a spread sheet that I used to generate some plots for my book. I'll put it up on my blog if you are interested.

 

[Steam]

Let it ride. If the yeast has mostly settled to the bottom you might consider giving it a swirl to get more back up into suspension, but I would not shake it or aerate after a few days of fermentation. The second beer was about 15% lower in starting gravity, and if there was equal or more yeast it would get though the short chain sugars faster.

If you would like I have a spread sheet that I used to generate some plots for my book. I'll put it up on my blog if you are interested.

Thank you for the advice , All the the beers i brewed before were high ABV , 8% + and fermentation activity was very intense for a long time , this is the first time i see fermentation slowing down so fast . Please post a link to the spreadsheet .

 

[WoodlandBrew]

In this spread sheet the cells with the orange background are made to be changed, and the others are calculated. The model is based on know interaction, measurements and also some estimations. It's should give you an idea of how things interact.

https://dl.dropboxusercontent.com/u/17759267/Fermentation Model.xlsx

And here is the blog post describing it
http://www.woodlandbrew.com/2014/05/fermentation-model.html