Hey there, bro! 👋 This doesn't look like a pH issue; it seems more like an overall nutrient deficiency or under-watering. I would recommend watering it not 300 milliliters a day, but rather 1-1.5 liters a day! At this age, the rule of watering 10% of the pot volume applies! Increase the watering; the plant is lacking nutrients overall! 👌😇👍 Good luck, bro!