just need a little clarification with ebb and flow

Hi, I have been searching the forum but unable to find answer to my question. My set up is 4 x 4 ebb and flow growing with hydroton in 6" net basket. My question is do I need to fill the rest of my table with hydroton as well or is it ok to have roots on the bottom of the table.
Right now I do have hydroton covering the table but it is spiking humidity in the grow room up to 75-80% RH, so I would like to take it out but if it is better with it in I will leave and correct humidity with dehumidifier.

hmmm... not really my area, potroast would be a good one to check with. You wouldn't have to cover the table with hydrotron, you do want the roots covered to stop light from hitting them. You could stretch plastic across the table and cut holes for the net pots, may do more damage to the roots than leaving them and getting the dehumidifier, but for next time....... VV