I haven't been following this thread really but figured I would contribute my experience last grow. I can't exactly remember why they started to slime but after they did I re-enforced the light proofing and added more air and changed out the stone. It slowed down but did not go away. When rot started I trimmed the root mass of all dead roots and then soaked in a H202 solution. It would be better for a few days and then get worse again. I realized it was because the H202 would stunt it but as soon as it dissipated it would come back. I started adding H202 to the rez every few days and also soaked the root mass in a stronger H202 solution once a week during rez changes. This slowed it down for a while but it kept coming back. As a last ditch effort I trimmed the roots again, soaked in a strong H202 solution, rinsed really well, and then added hydroguard to the rez. That worked and they made it to harvest. The brown slime caused a lot of nutrient issues so these plants had a long veg time but the harvest was decent. Getting those plants to something that was nice to smoke was very hard and took a lot of time (seed to harvest was around 5.5 months).
For those having slime or root rot symptoms I would definitely recommend hydroguard.
. Just found it much less stressful to run hydroguard and it really did bring the plants back from the dead lol. I tried everything and things didn't improve but the chlorine did help more than the H2O2 
