What I’m saying is at his stage he shouldn’t be ph’ing or adding nutrients.
Correct, especially since his water @ EC 0.1 is extremely soft - that is a good water for plants but warrants a handful of dolomite or algae chalk to the substrate, and then one is good to go (or CalMag with every feed...)
The pH 5 feeds are causing me a headache. Especially since I have no clue if he did really soak these pots completely full with pH 5.0 water full or just did add half a cup to these pots...?
I also feel he's not watering correctly, and that is a huge can of worms on soil, esp. with small plants under somewhat weak lights...
BTW @OP
as for your light's ppfd - it's ok if you grow forself but don't expect huge colas - rule of thumb for Cannabis in flower is 700-1000ppfd. But your ~500 are going to work as well, you'll see.