There is a lot to impart here, and we will do this over time, but let's start with
casing soil and layers.
First, cubes do not need a casing layer to fruit.
This being said, I still like to use them because the are good moisture banks
and they protect the sub from drying out in my dry area.
The classic casing soil is "50/50+". This is 50% verm plus 50% peat moss with
hydrated lime (the stuff that burns) and gypsum added. The lime is a fast acting
pH lifter and the gypsum plays the role of buffer, helping maintain the higher pH.
The fact is that the fungi do not really love the high pH all that much,
but contaminants like it even less and they do not have the foothold of
strong spawn to start from.
A casing soil is designed to be less (or non) nutritious. The idea is that when the
fungi runs into it, it is stimulated to reproduce by the change.
Regarding how much lime to add, years ago now Uncle Rico at The Shroomery
laid this one on me: for each cup of peat moss, one teaspoon of lime and one
Tablespoon of gypsum.
If you choose not to case, then you should feel free to let the sub begin pinning
before introducing it to fruiting conditions. This can help a good first flush pinset form.
One thing that I did see up-thread was the suggestion of using plain verm as
a casing soil. This is not really a casing layer per se, as verm is nutritious to
the fungi and will be consumed like the sub was. This tek works fine, and was
called the "rez effect" some time past. (as in "reservoir", as the verm hold water well).
What sort of fruiting chamber are you going to use?
Good luck,
JD