calcium deficiency? Background: Strain: canuk se...

I can’t tell what’s causing damage on your leafs but I can tell you that 4 plants in that box are going to suffer just because the won’t have space to grow. How is it possible that 2 humidifiers are not able to rise humidity in such a small box? Are the plants really 28” from a 100w light? That’s too much if you are using leds, plant will stretch a lot to reach more light.

could most likely just be from the humidity.. I wouldn't panic but I would try to get the humidity up somehow. rh 30 and 27 is definitely in the red zone for vpd. Causing high rates of transpiration. You might be able to pull it out and or help it with more waterings. I know this can be a dangerous game. But I don't think it's a deficiency. Especially if your growing in living soil and the medium is healthy. I mean Gaia makes some strong products so I lean more towards the Vpd being off. Your plant looks good for 12 days and you are right on track other then maybe the RH. The plant will eventually find a balance on her own so it's not like you need to panic and change everything you are doing. The First set of leaves tend to be abandoned first especially if things are off. If your seeing issues on the newer foliage I'd be a bit more worried.

Potassium or zinc? Calcium or spots all over I think

Fighting to get RH up I live in a cold dry climate, running 2x humidifiers outside the stealthbox and a mini desk top humidifier inside the box Plants seems otherwise happy