Help Ebb/flow system! Root question

Hello fellow growers!

I build this system where water is pumped up into the top box from the reservoir down below. Now i wonder if i let the roots grow down in the box where there is no soil and no water when its drained, will this work or would the roots have to be in soil?. I plan on using some pots with rockwoll and leca stones to plant them in, but when the roots gets to long they will just grow out of the pot. Can anyone tell me if this would work or not ?

Here is an illlustration of my system:

I just finished my first grow and it was an Ebb and Flow system. I put my clones right into 6 x 6 x 6 Rockwool blocks and just set them in the tray. No other media was used. The roots grew to about 1/2 inch coming out of the bottom of the blocks. No problems with any root-rot of any kind. I grew 5 plants to 2 1/2 feet and got 12 ozs. my first crop. I have a 2 x 4 flood tray.
Good luck with your grow.

So the roots just incapsulated the cube or grew free into the tray?

they stay in the cube. The roots only poked out about 1/2 inch. I used this method so I can freely move the girls around as I need to. This is how the guy at the hydro store said they can be used and I read about how others do this also. worked great for me. I flood the tray three times a day x 15 min.