DWC (rootrot) to soil?

As Hasy said. Make sure there is a small gap between your rock wool and water. As long as your bubbling the water the bubble splashes should be enough. Also, with water underneath, you don't need to wet your girl's., especially while lights are on. Just try to get your humidity up to about 45% when growing hydroponics. Freeze water bottles or coke bottles and place them in and around your rez to keep your water cool. If your using colored nutrients, they stain roots. Clear nutrients is best for hydroponics. At 82 day temps you should not allow your girls to go more than 10 degrees difference and 82 is slowing your plants growth. 76 is ideal. A extraction fan to remove heat would do wonders.

How old are your seedlings? I would definitively give soil a try if hydro doesn't work out.. I am assuming thats it's because of heat. How hot is your reservoir? It could be heat that causes the problems you're having. If thats the case "pro" thing to do is buy a chiller if you cannot afford a chiller freeze water in a Coca Cola bottle if you don't want to raise the water level that is. You can use regular ice cubes too

Oof.. I’ve done it but don’t recommend it.. last resort type thing. You’re just gonna transfer the issue to soil and have to account for that somehow. I’d just deal with what you have going on and try and diagnose the issue. If you aren’t seeing negative symptoms in the plant I wouldn’t freak out about a little root gunk