Trainwreck Fem Photo

There's a blank week, sorry about that. There are detailed pictures and explanations of the current situation. At this point, the older plant seems to be doing fine. However, the younger plant's growth has definitely slowed down. Suspecting potassium deficiency, that's why I increased the nutrient amount. But K deficiency might not be the only thing that's wrong. My pH levels should be fine, got a new meter and did calibrations regularly.