You're in good hands here but take it easy with that light, no need to add any extra stress until the problem is resolved. Personally I'd transplant the problem plant into a slightly larger container with plenty of perlite and regular soil to make sure the roots aren't suffocating. Wait and see what Rusty (or other more experienced growers) says about this before doing it.

Any way of measuring the run-off ph? If using the color strips or drops, tinted run-off will skew the results. Need a digital ph pen for that. Hope you get it figured out :jointsmile: