Well done good sir
I picked that trick up from one of the dudes @ my favorite hydro store.
So, how deep is your tray? It does look a bit shallow, but it's honestly hard to tell from a photograph. My buckets are only about 6" deep, but they're super wide, like 4-6 inches...so it could be the case that your setup is just fine. I see the 4" grow cubes...are those touching the bottom of the tray? If so, then you really should get more hydroton, if for no other reason than it will make the plant more stable. One of the issues I've seen in other hydroton grows (especially in planter-less ebb systems) is that the roots aren't able to "grip" like they do in soil.