Help with flood table..

So I recently let my bro set up a flood table, first time ever since I usually use RDWC and never had any issue.

So we have 5 girls in smart pots filled with clay pebbles, the table fills and drains for a total of just under 20 mins, every 3 hours starting when the lights turn on, and he set no feedings while the lights are off (not sure if that's right or not, I think they need to be fed at least once while they sleep no?) The ph is around 6.5 and the rpms are around 550. And I just switched over to try out this Remo Nutrient..

Attack hed are the photos of the girls 5 days after transplant into the table..

Now I think they are to dry and my bro thinks he's drowning them.. please anyone have some advice would be very appreciated. Thanks

Back when I did hydro, my plants were watered every hour, but I used flood and drain. I'd literally flood and drain the pots. They took about 2/3 minutes to fill and then pump would turn off and they'd drain quickly. Keeps the root airated that way.
Yours look to dry to me and you can see salt build up on top of the pebbles meaning they are drying out completely before being watered again. Which you don't want. They'll probably wilt for a while due to stress.
Just my thoughts, I haven't ran hydro in a few years though