Yellowing leaves

How is the humidity of your soil? pH lvl can also change because of water logging. The pics show saturated soil. Maybe you just watered them. In my opinion it's waterlogging causing pH change and maybe low power lights. Try watering less. Especially in the middle and bottom of the Container.

maybe low S because it is paling inside out. Mg deficiency would be interveinal with spots and would never display on a young plant because it takes 30+ days from the point an Mg deficiency occurs to the point that you can see a symptom on the leaf. Unlike the other nutrients, there is a very long delay between cause and effect. coincidentally epsom is still a good option since it;s 12.5% S that is 100% plant available or some percentage near that. Before doing anything, i'd observe these plants under normal room lighting. Does it still look pale? Grow lights tend to make plants look paler than they actually are. Regardless, if you can see it slowly progressing under the grow light over time (not just remaining the same, but getting worse), that's still a good reason to react. When growing in a soil, you need to supplement various things more so over time as it runs out of whatever nutrition came in the soil. It's a trial and error process for every product, as there is variation in what constitutes each product. Take notes of timing and what you did... if using same products from soil to fertilizer, you can make those adjustments in a pre-emptive way before you see symptoms in the future... within a few grows you should have a good process worked out. if you want to hit the easy button, go soilless or hydro. You run maybe 2-3 formulas at various points and when you provide 100% of nutrition, it makes diagnosing and adjsuting a faster process, especially if you track ppms of what you feed across spectrum of nutrients and not just some overall concentration. Gauranteed analysis labels are our friends.

Stop - put the cal-mag down! Here's why. Your plants are not showing any sign of calcium deficiency. Instead, use epsom salts at 1 teaspoon per gallon along with your feed routine during veg. Calcium needs in such a small plant is almost zero. Excess calcium in cannabis plants can lead to a condition known as nutrient lockout, where the plant is unable to absorb other important nutrients such as potassium, magnesium, manganese, and iron. This occurs because the high levels of calcium block the uptake of these essential nutrients, causing deficiencies that can harm the plant's health and growth. Calcium needs during the flower cycle are quite high. You can safely make the switch to cal-mag after you switch the light cycle for flowering ... or ... if you're growing an autoflower, when you see your flowers beginning to form. I see this recommendation all the time. It is not a good idea to use cal-mag during veg unless you are experiencing calcium deficiencies. Your plants show no deficiencies.

Also sehen jetzt nicht wirklich schlimm aus, du kannst aber langsam anfangen mit einem dünger der Stickstoff enthält zu düngen, nur in kleinen Mengen. Wenn du unter einer LED Lampe grows fang auch an CalMag (Kalzium und Magnesium) zu düngen. Sonst sehen die ja gut aus