Starter overflowing

[stosh]

Why would a starter that is not on a stir-plate that is manually shaken now and then overflow when a starter that is on a stir-plate does not?

I mixed up two 1L starters last night one using Omega West Coast Ale I 004 and the other is Omega Hornindal Kveik 091.

The 091 is on my stir-plate and the 004 is not. I just give it a shake when I can.

The krausen in the 041 has overflowed out and down the side of the flask (sanitized alum foil on this flask) and the 091 (on the stir-plate with foam stopper) has a good krausen but nowhere near over flowing.

Just curious as to why?

 

[Keith81]

I'm not familiar with either of those yeasts but some strains are more aggressive than others so it could be that.

 

[wyowolf]

I have started to use the foam drops in my starters, i have had a few that did that for whatever reason, now its much more controlled and i dont worry about making a mess anymore...

 

[day_trippr]

Because a spinning stir bar knocks CO2 out of solution so it never had a chance to build up...

Cheers!

 

[specharka]

Stir plates agitate the wort to keep the yeast in suspension, ferment the starter wort quickly, and build more cells. A byproduct of that is they knock out dissolved CO2 faster and disturb the surface tension of the wort. The krausen on a stir plate starter never gets a chance to fully develop.

I hardly ever see krausen on my starters anymore. Though I sometimes use anti-foam, even the starters that I omit it from barely foam — maybe 1/4 inch above the wort level maximum.

 

[kh54s10]

I have been doing step starters on a stirplate from very small samples on the first step (frozen yeast bank). I get almost nothing showing on the first step. A little foam around the edge on the second step and quite often blow off on the third step.

As said some yeasts ferment a lot more actively than others.

 

[stosh]

Stir plates agitate the wort to keep the yeast in suspension, ferment the starter wort quickly, and build more cells. A byproduct of that is they knock out dissolved CO2 faster and disturb the surface tension of the wort. The krausen on a stir plate starter never gets a chance to fully develop.

I hardly ever see krausen on my starters anymore. Though I sometimes use anti-foam, even the starters that I omit it from barely foam — maybe 1/4 inch above the wort level maximum.

I never had krausen of any real substance form on my stir-plate starters either until I used this Omega yeast. Ultimately both starters took a ride on the plate and both boiled over. I'm brewing with one today and the other tomorrow. Maybe I'll start with a blow off tube...