Good evening I am currently in the 4th vegetative week of my first grow. I have a 1m x 1m x 2m, 400W HPS, approximately 40 cm from the top of the plants; the temperature is around 27-28 most of the time, humidity a little low, just around 40%. Today I noticed yellow spots on some leaves and also some leaves are curling up. I watered the plants 4 days ago with a little nutrient added (50% of the suggested dosage). As you can see the moisture meter shows that the soil is still wet. I think that these meters are garbage and that he plants need food. Am I right? Thank you for all the tips. The first pic is my best baby.