Babushka and Diesel Auto

Been trying to keep humidity and temperature steady which can be challenging with closet grows. Managed to keep it consistent(for most time) temperature of 30 celsius and 55-60 humidity throughout the day. Over night temperature dropped to 21 celsius couple of night but fixed it and now won’t go under 24C. Also humidity went up to 81 over night few times but with fixing temperature now is better, and is around 70. Been feed with filtered water every 4-5 days. Last two waterings been fed ph of 6.6 and 6.4 around 0.5l each Babushka seems to be ahead with about 3 days. Babushka showing some signs of possible nutrient burn or ph issues? See tips of new growth.