High there BEB, Howzit?

I'm willing to bet that your PH is quite high thanks to the untreated Hydrotron.
Rockwool? same problem.
But mostly, it's the distilled water that's killin' ya.

Without some mineral content, it will literally, suck the life out of your plants.
Bring it to 250 ppm. with CalMag, then add enough GH to bring it to 600ppm.
That should put your PH in the right neighborhood.
You might be able to salvage something, but at this point, I'd start over and treat the Hydrotron and the Rockwool first.

If yours came sans directions, simply soak them in water with a PH of about 5.0 for a few days, then rinse very well.
(The conditioning will release more of that red dust from the clay pellets.)

Maybe only one cent worth, but, might help buy some thumb paint.:greenthumb:

Aloha,
Weezard