Can't pinpoint the problem

Okay straight to the point , using a 400w HPS at 16 to 20 inches away from plant top , plant is 4 weeks old almost , 6 inches tall nearly , bottom 2 leafs going yellow and dying curling upward , 2 leafs further up with a little brown spot not much but also a bit of yellow on them only 4 leafs are effected with this yellowing , most leafs if not all have a hook pointing down on leaf tips , some stems appear purple in color but was like this from start really with no problems

Temp is 85f with light on , about 78 with light off
Watering every 2 days , pot at the moment is 1 gallon i believe , using 200ml of water every 2 days , 1ml white distilled vinegar to lower PH , Using Still "Highland bottled spring water" , when feeding with nutrients i add 0.5ml of my solution per 500ml , bottle says 1ml per 1 Litre which is "Power Boost Plus Power bloom" ,

PH is about 6.0 to 7.0 not accurate reading using the Test tube kit
Soil is Plant magic plus Organic Grow

Lights on 17 to 19 hours a day darkness for rest ,

Strain is Blue cheese i believe seeds came from friend from donor plant
I have pics but I'm a bit slow on forum use and don't know how to attach pics i use the image code but never seems to work will try with the 4 pics i have

This is my first ever grow so lacking a little experience

Any help will be greatly appreciated as I'm struggling here and worried this might get worse

for starters, it looks like nute burn, soil may be a little too hot. next, temps are a little high, might want to back that 400 hid light another 4-6". 3rd, what is you relative humidity like? last, i suggest you invest into a ph/ppm meter to avoid a lot problems, if you can, pick up a blue lab meter.

I still haven't got a humidity reader yet so could be the problem , i also need to invest in a soil moisture meter ill be getting one 2morrow a combi PH and Moisture meter , so that should help with temp and dryness of soil ,

Thanks a lot for your help man , i believe this could be nutri burn as i remember the other day i added more nute than i usually do to my feed hoping for a little boost i usually add 0.25ml per 250 ml of water this time i added around 0.525 ml to my 250 ml that's over double the recommended dosage lol the bottle recommends 1ml per litre so that's 0.5 per 500 ml 0.25 per 250 ml , when i water i usually use 250 ml of water in a jug , i know now rushing can cause major problems best to be patient and let nature take course

Thanks a lot for taking time to reply to this dude appreciate it a lot , i will lay off nutes for a few days and see what happens its gotten worse since i posted these and i ain't added anymore Nutrients since i posted this ...

These are updated pics with a little better quality incase you see this again , this may help you confirm if its nute burn or not !!!!

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Thats nute burn fella.
Remember the very basic. They're weeds. Let them be weeds. We tend to mess 'em up when we don't leave 'em be. Back off the nutes for awhile and just give them some plain water, but only when the pots feel light and they need it.