Obvious pH issue imo. Hope you got it figured out by nowPictures would be helpful..
Maybe for pH They are not great but I don’t think I used mine properly and I have seen some people getting results for pH, not sure the accuracy on it but they depended on them to grow plants. For moisture they are really accurate/consistent and for pots that can’t be lifted, are a decent option.I've never had one of those meters work correctly. Lifting the pot is best, your problem looks to be a little dry and possibly the light is a little to bright or close for that young plant.
Hate to be a "spoil sport" throw a way those meters - (money grabbers) to check for watering use your finger ( dry up-to second nuckel - OK) also as mentoned the feel of your pots (heavy or light due to amount of water in them) some are heavy drinkers some not just like feeding them some are heavy eaters and some not) just keep it simple Indoor growers tend to over-do things - myself included - experience is the only answer
Not sure how either of those methods will help at this point. In a 10 gal air pot.with 1/4 -1/2 inch of garden sand on top. Lifting this sucka isn't an option and the knuckle test is less then affective. With the sand on top. Ive just been watching both the water meter and the leaves and trying to listen to the plant more than anything today.Hate to be a "spoil sport" throw a way those meters - (money grabbers) to check for watering use your finger ( dry up-to second nuckel - OK) also as mentoned the feel of your pots (heavy or light due to amount of water in them) some are heavy drinkers some not just like feeding them some are heavy eaters and some not) just keep it simple Indoor growers tend to over-do things - myself included - experience is the only answer