My flowering plant is dying due to the bad drainage system

Sad to show you my dying flowering plant due to my careless work of the drainage system.
It's been flipped into 12/12 two weeks. Yesterday, it looked not good and I thought it must have been the light problem and then adjusted the lamp higher a bit.
But the girl seemed worse this morning. And then I checked out the nutrient and hydroponics system.
It was becuase its roots grew toward to the drainage outlet and caused it become blocked. The root has been soaked in the water for a long time and become rotten....

I dont understand, my roots are in a resoivoir at bottom always competly submerged in water and healthy? Air stone the difference?

get alot of air pumping to them roots

so why is it that the stone stop from drowning as long as 02 ich plenty is ok,,, does this mean exposed roots fully submerged is better?

Because the stone adds oxygen to the water, which stagnant water loses.

i would suggest just to pull up the whole thing and give the roots a trim, and then rotate so the roots aren't on the side of the hydro system drain holes. stay positive bro! ^_^