I have 2 pumps in the tank . one feeds the dripper on the timer and the other is constantly running in the rez tank and feeding out to a water chillerSo your VPD now is better. I like the higher RH at this stage.
30 seconds seems too short and 2 hours too long to me. Seems like with nothing but hydroton there is no way to get them wet enough and keep them wet. I'd worry about my roots drying out. I don't think you can overwater at this point, but you could underwater.
The only drawback I see to running the pump more is possibly heating the water too much. What are the black hoses going out of picture? Is that a chiller or filter or something?