First time grower needs advice. Have pics

Hi there. I've read quite alot of the posts in this section on leave yellowing and curling round but would like some advice on my own plants/setup. I've got some photo's and this is my setup.

1- box size is 2x3x5 foot
2- 400w hps light with 200cfm exhaust fan attatched too carbon filter
3- humidifier set too 60% but not sure how effective it is as it just been added
4- water when soil is dry 2" deep
5- 4 weeks old
6- just had there first feed yesterday as had delivery problems
7- 6" oscilating fan inside the box

The first 2 pics are of the older of the 2 plants (only by a few days) and the last pic is of the humidifiers position. Thanks in advance and I will be here to answer any questions.

did they look like that before you fed? looks like nute burn. lights are probably good 'cause it's the lower leaves that are burned the most.

what is that soil , Bark chips? Nutes for sure

flush em through bro take all the dead shit off to

They got there first feed yesterday at 1/2 strength and i didnt think of nute burn because they hadnt been fed yet. I bought a multi purpose soil that had perlite added but didnt realise it had its own nutes in it. Another school boy error from a newbie then?

Should i think about transplanting them or will flushing that soil n feeding them the proper nutes be enough?

Thanks for all the quick replies and advice.

you should be ok to just flush em and carry on flushed until you see the first bit of new growth an hit em with some more nutes

the plants have actualy be growing at a steady rate from seedling and i've not noticed any stunted growth.

Could this be due too low humidity as i just put the humidifier in on wednesday and these problems showed up before then.