You can lose those roots on a plant this young, not good but they will live. But I would give your nutrient program a look over. I've ran hydro for 20 years and not seen this amount of slime this quickly. There has got to be some light reaching there as well for that volume to grow overnight as well.
Go with a 3 part hydro fertilize program. They will have everything the plant needs, I use
Technaflora and there are several other reputable firms.
F/D stands for flood and drain. My plants sit in hydroton w/ rockwool cubes, just like yours. Water is pumped up fills the tray sits for 30 minutes then drains back down. Repeat every 3 hours. Separation of light and water is critical for this method and yours as well.