Nute Deficiencies in Seedlings?

so what you are seeing is your ph is off, you got it early so here is the fix. next time you water, water until your run of is at a 6.0 ph reading, now let her dry out for a day or 2, when you water the next time use nutrients, a very small amount including cal mag in the mix. your plant is at the age now as it depends on nutrients. you should start seeing a improvement right after the first feed. it is no different than your other grows. hope this helps.

я думаю проблемы с ph

No nutrients. Mars hydro led at 24". 6.5 ph water. I'm thinking maybe a bit underwatered?

Usually seedlings don’t need many nutrients during the first couple weeks. It might be a deficiency possibly caused by nutrient lockout due to ph or other factors. More info on feeding, light, ph, etc will definitely help!