The question - How can I store the tank safely - I Hear that if not done
right the silicone seal will dry and crack and therefore I may run the risk
of a leak when I re-fill etc.


You're hearing an old story from when tanks use to be built
with metal frames and tar to hold the glass in. Those did
dry out (they'd dry out even with water, but detritus would
plug small leaks). Left dry for a few years almost guarenteed
a leaker.

Today's silicone doesn't dry out, in or out of water.
Go ahead and store it.

Bob