Space used by individual rockons

I have problem with space on my system drive.
On my system drive i have rockstor and main rockons service share.
Rockons configuration and data shares are located on a bigger raid 1 pool.

Is there a way to see space used by individual rockons on the main rockons service share?
Any tips on how to cleanup?

In the end i moved the rockons service share to another drive but what did help a bit was the “docker system prune” command. Perhaps there should be a prune command that runs on schedule in rockstor?

Also i think it’s strange is that the share was taking up 20GB just for 4 rockons. It was growing over time without installing new rockons.