Yup...no nutes till 4-5 internodes...then start at half-strength. In the wild, they don't normally get full-strength nutrients handed them on a silver platter. They have to go looking for it. Plus, 'normal' soil nutrient content doesn't even come close to the nutrients we add to our potted plants.
Right now...you are burning your plants root system, and stressing the shit out of them.

Why are you not using tapwater? Unless it's really nasty...it's usually the best/easiest way to go. But regardless...what's the ph of the water you use?

Cannabis prefers a wet/dry cycle. Water them to slight trickle out of the bottom, then let dry before watering again. Squeezing the cups will compact the soil around the roots, and you risk damage. (bad idea)