No bottled or distilled water, just use the tap water. Next time the pots feel light, do a good flush with tap water and adjust the pH so that the runoff comes out at 6.7.
Then water immediately with a GROW fert at 1/4 strength in 6.7 tap water.
Is that a coco-based medium or what brand? It does look like you could have a calcium problem, which would be caused by either too much distilled water or coco in the soil or both. If you have CalMag plus, add that to your feeding for now. If not, scratch just a couple pinches of lime into the soil surface. You don't need much, but you do need SOME source of Calcium.