You might want to go easy on this for beers you want to keep long term
to (in theory) minimise mixing oxygen into beer that will cause oxidation
of beer/staling. I think stirring in little circles along a big circle around the
tub (circles wthin circles) and then giving it 30-60 minutes before bottling is
enough.
And don't use PET bottles for long term storage - they let air in through the
plastic - I have some beer in PET bottles over a year old and they definitely
taste sherry-like (oxidation).
If you can be bothered, you could use the container with markings to mark your
cube(s). Fill container up to 25L say, pour 1L into cube and mark with permanent
marker pen ... and repeat. You might want to put specific scratches where the
marks are as the the pen marks will probably wear off.
I've done this with one cube with one set of marks for cube in upright position
and another set with cube on its side - for when you want to do this:
:huh: !?
