The leaf curling is nowt to do with ph, when the leaves curl up, gnarl or twist like that its often because fan is too close or blowing constantly too hard onto that plant, the leaf starts to curl inwards or twist because its drying out, its an attempt by the plant to reduce the surface area of the leaf, reducing transpiration of moisture, and slowing down the drying out of the leaf, perfectly normal and nothing to worry about, called wind burn, my two jack flashes were wind burnt on every leaf up until about 5 leaf sets when the plant could handle a bit of strong breeze from my oscillating fan.
And a pic of her taken a few days ago, no ph checking or adjustment.
PH checking and adjustment is a complete waste of time and money when growing with most composts these days and will do more harm than good, leave it to the hydro boys.
The little'uns to me just look simple hungry, looks like theyre in a light seed mix in a small pot?? id get them potted on into a bigger pot of stronger compo asap and the new growth will be lush green again.