help, i dont know what i'm doing wrong

So I have 6 plants going and they all get fed the same thing, but 2 of my plants are super sick looking. I brought pictures to local grow shop and he said that they looked like they weren't getting enough nutes, so I fed them heavy for a week or two and no change, so I flushed them both out. I just am at a loss the other 4 plants look great. I am a complete newb and this is my first grow, I have a small tent running a 400watt mh 18 hours on time, fox farm nutes and fox farm ocean forest soil. I use miniuim ammount of nutes per gallon and only give them nutes once a week. I have a carbon block filter just for my plants water, I do not have a ph monitor yet, my funds ran low hahaView attachment 2424028View attachment 2424029

maybe over watering, or maybe your heat is to high in your grow room. other than that i dont no what to tell. someone will know what it is.

The room usually is at 75 degrees and I wait to water till it is super dry and light, I just don't know what the heck is going on

Would those 2 sickly plants happen to be sitting directly in front of a fan, thus drying out faster?Do the leaves feel dry or crispy?Try not waiting so long between watering those 2 that are sick.

How close is your 400 to the tops of the plants? A couple look like they have some bleaching going on.

not 100% sure here but i thought that the lime green look has something to do with nitrogen but whether it is to much or to less nitro i don't know for sure.. hope this helps some

They are kinda by the fan, do you think they have a chance of getting better? I thought the bleaching may have been from too much nutes that's why I ended up flushing them all. There at least 18 inches away from light the air above them isn't hot feeling..

Looks to me Ph and over watering. Invest in a good probe. Back off the nutes a bit. If shes locked out your probably just burning roots.

I appreciate all the feedback, thanks guys.