Ok, Thanks.
In DataCenter, Storage, Add, ZFS, the only pool shown is /rpool and it's subs. My other ZFS pool didn't appear.
I tried this and got an error:
root@pve2:~# pvesm add zfs -type zfspool -pool z3tred
400 not enough arguments
root@pve2:~# pvesm add zfs z3tered -type zfspool --pool...