1st grow - Stone and CBD

So, about week 1 of my grow. My babies are growing, I can say that. On the other hand, it seems they are a little bit on a smaller size (at least compared to other people's pics). They got to about 5cm now, and all have added a pair of leaves. They are nicely serrated. Some already started working on their 3rd pair. Huhu happy days. I am not watering them too much, weighting the pots and checking the simple 3-in-one meter (the one that measure soil pH, illumination, and moisture). When I do water, I simply add water until it starts dripping from the pot, wait a bit until all dripped, and then place them back in their compartment. Since one of the BLs started curling her leaves as well as turning it brown I decided to put a transparent plastic bottle over it. It might be the effect of a heater. I also added a small ventilator to the room but unfortunately it runs out of batteries fairly quickly so I will need to fix that problem and make some amendments so I can connect two Ds instead of two AAs there. It might last a few days then. If all goes well (i.e. if they reach about 10+cm) I will replant them next week and move them to the grow room with the LED lights. I want to add some nuts in their soil and give them bigger pots. And now for the sad part: - the two seeds that eventually cracked (later than the first batch I mean) don't seem to grow now. Although one, Mimosa Lemon, did manage to get out of the soil, it is now stagnating. The Northern Lights one didn't even manage that. Not happy - I gave up on the remaining three seeds (one Mimosa Lemon and two Northern Lights). None cracked so I took them off the paper towel, however, as I didn't want to just throw them away I put them in the pot. All three in the same one. None managed to get out so far so if nothing happens in the next two weeks I will make room for something else. Update: So, I've noticed the other day some yellow spots on my BL No. 2 as well as very light green colour and I suspect it is the result of a nitrogen deficiency. Of course I am not sure about it but nevertheless I decided to add some nuts into my water. I used 15ml per 4 liter of All purpose Miracle Gro Soluble Plant food with N-P-K values 24-8-16. I watered all of the plants with the solution and my leaves all turned much greener. Fingers crossed I am not wrong about this.