Yellow and dry leaves, help !

Hello guys, this is my first grow. It's going well overall but I have a concern with the newborn leaves of my 3 plants :

My setup ; 4 32W T8 CFL, grow tent 5X5, small air fan, I used soil that was treated especially for tropical plants ( that's what they wrote on the package )
The 2 biggest plants are about 40 days and they have a different kind of issue than the smaller one ( in my opinion ), As you can see on the photos, the lower leaves are yellow.
I have never added any fertilizer to this point on any of my plants, I think it might be the issue and I should start using some ?? Also, you can't really see but all the upper leaves are kind of blocking light to the one who have issue... this is somewhat negligeable imo because the CFL surround very well the totality of the plants.

As for the smallest plant : The lower leaves are suppper dry, I almost flooded the plants couple of times to make sure theres no water deficiency, after 2-3 days, the leaves are still dry as hell. I broke part of it just by touching it.
I think I should be cutting both of them to let space for new growth, what do you guys think ?

Thank you very much

can you post a pic of the soil bag?.. whats the temps..comfortable ( i assume because your not runnin HID) what kind of water? from tap?

Temperature is 21-26 celcius, it's tap water but I live in a city that won man international prizes for the quality of tap water...

I can't send out a picture of the bag as of right now... I threw all of them away but i'll go take a picture directly at the store when I'm available.

if your talking about the first 2 "pedals" that start when it comes up?!...if so those naturally always die off. no worries!! mother nature at work..dont fuck with her. continue your grow as scheduled

Do you have acces to the knowledge and the kindness to explain why ?

Also on the smaller plant, I feel like thoses leaves should be taken appart to let space for new ones, what do you think ?

you'll have to ask the Gods for that info..as i do not have it. I personally feel that your plant is too young to start defoliating it but opinions will vary on that.







this is the size i usually start defoliating leave and it can also be done sooner

I will read more on that subject, thank you very much. You've been helpful.

FYI, my biggest plant is about the size of the first one on your picture (your smallest)

i keep it very simple..coco coir soil. flora nova bloom for nutes. EWC tea(supplements bennificial bacteria) and leave them alone .....that is the hardest part

if i would recommend any thing it is this https://www.rollitup.org/dwc-bubbleponics/361430-dwc-root-slime-cure-aka.html