Need some help

Hello I'm growing for the first time and noticed some changes in my plants that I'm worried about.
Soil is ffof with added perlite,and cut with non nute added potting soil.
They are under a t5 ho 4ft 8 bulb fixture, usually water 2 times a week when the first 2 in of soil feels dry.
Im using ff nutes very lightly once a week when watering, the other watering is done with filtered tap water with a ph of 6.5
The soil ph fluctuates between 6.0 and 7.0
Temp is 78 degrees with 60 percent humidity.
The leaves are dry feeling and cupping some, yellow spots on lower fan leaves ,some lower leaves are completely yellow.
One plant is 1/2 the size of the other 2 and really light green and sparse .
All three are ak widow 47 cross feminized seeds.
Plants are 4 weeks old. I did some research thought they may have newt burn so I flushed all three plants. Been 3 days since flushing and no noticeable change.
Any help would be appreciated.

looks like the start off nute burn, with the deformed leafs appearing and they are puffy because they are trying to dissipate as much water as possible.

e.g plants can sperate the nutes from the water not matter how much you mix it. if they are drinking the water and leaving the nutes in the soil its getting pritty toxic in there!!

soil will take about 7 days i belive to show signs off healing if you are feeding twice a week stop and feed once a week with nutes and the second time with phd water.

soil holds nutes for frickin ages, its like a sponge!!!

Im only feeding 1 time a week and very very lightly

It doesn't look that bad yet. I wouldn't feed them again until you see your first yellow leaf on the bottom.

I've got to get me some of that FFOF next week to add some excitement around here. Peace.

newbiegro said:

Im only feeding 1 time a week and very very lightly

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At 5 weeks, I would say you can go ahead and start feeding.
All the leaves are starting to get a little light, and with the yellow tips, I would say the early stages of a Ca. deficiency.
When you say 'yellow leafs on bottom', do you mean the cotyledons? or what?
Can you give pics of yellow in question?

Yes I'll get pics of the leaves in question. The leaves are curling inward and kinda paper feeling.