Hey quick when you were showing the roots, I noticed the water level might be a little high, if the stem of the plant is constantly moist it can start to rot, so I like to run the water level down making the roots chase it to the bottom, I usually run it 2 inches below the net pot. The way we get the plants through is run some benificials to hopefully stave off bad bacteria. It's Res change then refill with new nutes and Plus-O turn the lights down a bit for recovery then if no improvement after 5 days we res change again. Until we see improvement. If your curious after harvest split the stock where it was in the net pot and if it's black, slimy, and stinks inside it was stem rot.