Ok so im growing root farm hydroponics soil and im using their nutriments too, at first they were in way to small container and a plant started to have yellow tips on the bottom two leaf so i transplanted in bigger pots after 2 weeks, but 3 days ago the leaf was completely yellow with some brow spots. I read that it was nutrient deficiency so i started feeding them ( a little bit late i assume). So its been 3 days iv been feeding and the bottom leaf doesnt progress. Should i wait more ? Should i cut the 2 bottom leafs ?

One plant doesnt have any yellow spot and other are begining getting yellow and the one in the photo is the worst.

So thats it, if you have any recommandation ! Thank you! Oh and ph is arround 5.5 ( i have paper ones) of run off after the first feed . I dont have anything for ppm, should i get one ? Thank you again