Help with minor deficiency?

I would fill out a questionare but i can get to the point pretty quick. This plant is 16 days old from seed in FFOFS. No nutes in water...ph is between 6.4-6.6. This deficiency has started at the lower leaves..but has not affected the upper leaves..in fact the upper leaves are greener than all the other plants. But i want to stop this def from spreading...im sure many of you have seen this one. I repeat...all the nutrients my plant is getting are from the nutes already in the soil and from its cotyledons.

Could it be root bound and not a def.? Or is it possible you dripped water on the lowers when watering? .. apoligize not much help with def.

happy growin

I dont think shes root bound yet...im hopeful its something epsom salt can fix i am doing more research into it. Any other advice would be appreciated!

dont give her epsom salt.. that stuff is too strong and if thats not the problem then itll cause more problems for u.. i think its normal for that lower single leaf to do that, i think theres some possibilities.. maybe that leaf is not getting enough light.. if u think its a cal/MG problem (MG since u want to dose it with epsom salt) use azomite powder instead. itll give over 70 trace minerals including calcium and magnesium, but its an amendment meaning its hard to overdose it and if the plant doesnt need it it simply wont use it. just add a tablespoon of azomite to a gallon of water, and if u have any worm castings add a tablespoon of that to that gallon also. once a week is fine.

i would transplant her into a bigger pot at the size she is now unless u are trying to keep her small, the cup size can contribute to that also. i notice my plants start doing that in the red cups early also after only a couple of weeks.. they are usually ready to upgrade to a 6" mesh pot where they will stay for another 2-3 weeks before going into a 3gal pot. as long as the top growth is healthy that is what is important so i wouldnt worry about those 2 starter leaves withering, adding epsom salt has the potential to fk up the new upper growth, and then u have a major problem, losing lower growth isnt taking anything from the plant, it just means the plant has determined the amount of energy that leaf is producing is lower than the amount of energy the plant is using to keep that leaf alive.. its perfectly normal to lose some leaves during the plants cycle, and u dont have a problem until your new growth is coming out looking messed up.