Need advice about flocculation

[KamBrew]

We have a small factory. One-tank method. We cook a light lager. I use the method of assimilation, assimilated and harvest yeast 20% by 80%. I get 15 mil.cell / ml at the begining of fermentation. Before the filtration, after all yeast removals, there were 8-14 mil.cell / ml. now this number is 20-28 mil.cell / ml. from this problems with filtration.
What can cause similar problems and what can I do to fix this?

 

[Nosybear]

That's quite the trick! My guess is you got some of the yeast off the bottom. Otherwise, your yeast propagated itself by a factor of about 2.5, not a mean feat even if you intended it!

 

[KamBrew]

That's quite the trick! My guess is you got some of the yeast off the bottom. Otherwise, your yeast propagated itself by a factor of about 2.5, not a mean feat even if you intended it!

On third day i got from 60 to 80 ml cels/ ml.
I start with 8 - 8.5C, fermentation on 10C, it takes 7 days to reach final degree of fermentation, thene i cool it down to -1C
During filtration I measure cell volume at beginning and at the end, cell volume nearly same.

 

[Nosybear]

Filter size too large?

 

[KamBrew]

Filter size too large?

No filter normally handled up to 16 million cells / ml.

I lowered the temperature to lower the formation of higher alcohols at the beginning of fermentation, can this affect flocculation?

Maybe I should increase pitching rate?

 

[Nosybear]

Flocculation and filtration are different animals. Failure to flocculate would clog your filter but would not affect the number of cells passing through. Hence, I think you either tore the filter media, it wasn't installed properly leaving a gap the wort could go through or the filter size was too big. Those are really the only conditions that would let yeast pass through the filter into the "filtered" carboy, particularly in the numbers you mentioned.