K1V is practically indestructible...

You will probably need at least 1 gallon to replace what you rack out
once it settles down because K1V settles pretty nicely. There are a
lot more solids than you might expect in the first rack. It should
finish up in a few days and start to settle down. You will be better
able to predict how much you need then. The day before you rack take
the carboy and twist it sharply to get some of the sediment on the
walls to settle too.

Joe