Vmware sees the volume as empty.
But Equallgic thinks it's full. What the hey!?
1) Make sure there is no data on the volume that you need. Check twice. :)
2) Remove the volume from vmware.
3) Log into the EQL GUI, delete snapshots of the volume
4) change the volume to "thick provisioned" ( volume - modify settings - space tab - uncheck "thin provisioned volume")
5) set volume offline (right click volume - set offline)
6) Log into the EQL command line interface (via putty or whatever), and type the following: "volume select
7) Now go back into the EQL GUI, expand the volume back to the size you want, thin provision it again, and add the storage back to vmware.
Here's a screenshot of the volume afterwards. Free space again, woot!