in a tray????
what medium??
what flow rate????
rockwool requires say 50 ml a day for small plants average, so the drippers set at 2 litres an hr for five minutes every three hrs1 no feed at night!,
however in arlita this would not be enought and a feed at the same rate could start at 15 mins drip every three hrs,, all these will ned adjusting as the plant grows!, dont overwater rock wool! alow it time to drain down and dry a little too, saturated rockwool means no air to the roots and a dead plant!

try giving some more info!
a nft system flows cionstatly!

welcome to the world of endless possibilities,,,,,hydroponics