Yeast Pitch Stratification

[Jimmy Orkin]

This happened yesterday with the 10 gallon lager batch I made. I am using a 55 liter (13.2 gallon) Fermzilla which is much taller than a 6 gallon carboy.

I had chilled the wort down to 50F with my glycol chiller. I am guessing the yeast was about 60F, still cool from refrigeration. I pitched the yeast into the top of the FZ. 3 hours later the yeast was stratified at the top of the FZ and I was seeing some krausen on the surface. My Tilt, floating at the surface, was report temperature of 58F. I believe the yeast was fermenting warm in the top yeasty layer.

I bubbled CO2 from the cup on the bottom to mix the yeast in. I think bubbling CO2 will become a regular step in pitching the yeast in the FZ.

Anyone else see something like this?

[James Smith]

Since I can’t see it in stainless, not sure. I wonder a) what the commercial brewers experience, and b) if when fermentation really kicks off, does it rectify itself through natural movement in the fermentation process?

[Jimmy Orkin]

This is the second time I have seen this. The first time I tried swirling the FZ, did not work and finally did the CO2 bubbling.

This time I saw the layer and was just waiting to see what would happen. When I saw the krausen on the yeast layer I decided to hit it with CO2.

I did read an article somewhere that this is an issue for the commercial brewers and that they did things to mix the yeast in the tank.

I am sure that as fermentation progressed, it would mix on its own. My concern was fermentation was occurring in the warm zone at the top at a temperature that was higher than I wanted.

[James Smith]

Is this then a unique issue with your coiling cool configuration and placement? Would this happen in a jacketed fermenter or inside a chamber? CO2 seems to work to mix things up. I’ve used a pump to recirculate hops in the fermenter.

[Jimmy Orkin]

The picture below is similar to my configuration. The picture shows a 7.9 gallon flat bottom FZ. Mine is the 13.2 gallon with a dump valve so the coil is towards the bottle of the FZ.

Now that fermentation is going, I see lots of movement so I think stratification will occur again.

fermzilla_temp_twister_cooling_heating_coil_2-550x550.jpg (32.27 KiB) Viewed 577 times

[Terry Olinger]

I brew in stainless as well, plus pitch the yeast in the kettle like we do on the big rig since I use multiple ball lock kegs as fermenters.

Do you oxygenate afer pitching the yeast? I would think that would do some mixing.

[Jimmy Orkin]

I oxygenate with a wand and a 20CF welding O2 bottle. I do the O2 first then pitch the yeast. My reasoning is to keep the yeast off the O2 stone and want to keep pure O2 away from the yeast. It may not make any difference.

The CO2 bubbling is quick and easy and will probably become part of my yeast pitching procedure.