Water stress or calcium??

Hi everyone! So I have a little issue I have not seen yet, I'm guessing it's water stress ( and read up possibly calcium deficiency) just not sure what yet. So I'm in 3rd week of veg 600w mh, using cocoloco soil mix. 70-76 day time temps 66-70 night. 55/65% humidity day 65/75% night . Only gave 1 light feeding age old grow veg mix. Rest has been plain ph'd water 6.0 to 6.5..also 1 feeding silica very light as well. And 1 foliar of cal-mag. They are in half gallon pots watering every 2 days it seems.lights are 18"s away Any pointers would be helpful thanks all!!

Hi no I don't check ppms not sure what that is ? so over night my other plants are looking better from moving fans around. Although I though maybe I didn't water enough so I gave 1 plant plain 6.0 filtered water and now looks worse.

let your soil dry out a bit watering too much

Yeah I've been trying to watch it close.just transplanted to bigger pot so figuring out how much to water

let ur pots dry out b4 watering next time .

I let them get pretty damn dry, possibly root bound? 1/2 gal is what they are in now roots are coming out the bottoms already? 6-7"s tall