What is a difference in 4 gallons filled keg and keg filled with 5 gallons and 1 gallon removed through the tap couple weeks later? In both cases there is CO2 above the beer.
I only store (freeze) yeast from a starter I make before brewing. Never yeast from a slurry after making the beer.
I just make 2x bigger starter when I need to store. Stored yeast is always clean.
I am pretty happy with BeerSmith I use for many years. This is how it shows my last beer. I used less water then recommended. Only 8.25 gallons. Measured OG came quite close. What really counts is if the beer tastes good :)
One has to think about heating the pot, too. I forgot last week to put in a dummy bottom and burned a hole in the bag. A small problem :) Got a new one ASAP.
I use Avantco 3.5kW induction burner, so the pot must work with it. The way I used to test compatibility was to use a fridge magnet. If...
I use 60 qt pot for 5.5 gallon batches. One needs to start with ~8 gallon of water and ~10lb of grains for average batch. Grains take extra space in the kettle.
With expired dry yeast I always make a starter. With last pack, even fresh, I make 2qt starter. 1qt goes to the beer, 2nd qt I use to make 5-6x 15ml tubes for my frozen yeast bank. I do that like described in Freezing Yeast
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