It’s more the base of the stem staying too wet which undermines it enough for disease to take hold. Roots like to be wet but not necessarily all of them submerged. If you have sufficient air bubbling up it will wet the bottom of the net pot with oxygenated water droplets.
You can try, but the thing with bucket hydro (dwc) is the lack of nutrient volume. Later on your plants will be drinking a gallon or more, a day which means topping off daily (PITA). That’s where a lot of hydro growers go to RDWC and add both a reservoir and a chiller.
You can also buy a big yellow-topped tote and use that instead of a bucket: 29 gallon ones are used quite a lot and their cheap.
This light will almost flower off one plant FYI. It will be fine for veg but not quite enough to give you dense flower.
You are also going to want to run cal mag in hydro as the GH doesn’t supply it in it’s base nutes. Your TDS is about where I’d want it with that nutrient line.
One thing that can slow a plant is PH being off. You will see this as well later in it’s life cycle and again the only way to combat is to have more nutrient solution in play. Also; it’s a good idea to run a calibration on your PH meter as they can drift. Store the meter in storage solution to keep the glass bulb from drying out and cracking.