plants wont grow???

How long has this problem been going on? half a year
Are you growing in a PVC grow tent? (example: Hydrohut or any other non brand tents) hung mylar up
What system are you running? (DWC? Ebb flow? Aero? Water Farm? Flood Tables? and so on...) the areo 2 20 with foggers
What STRAIN are you growing? ak 47 and auto flower onix
What was the establishing technique? (Were the seed or clone?) seeds some are clones
What is the age of your plants? big ones are years old and small ones are 3 4 months
How long have they been in there mixture they are in now?(coco,soiless etc..) big plants were transvered from soil 6 months ago
How tall are the plants? 2 feet and 4 feet
What PHASE are the plants in? (seedling, vegetative or flower) are the plants in? veg 24 hours
What Technique are you using?
What substrate/medium are you using?(Hydroton, RockWool etc.) hydrotron
What is the Water temperature? 68 kept cool by mini fridge with cooling init in res see pics
What color are your roots? White? Brown? Are your roots slimy? kinda brownish
What Nutrient's are you using?(If growing soiless) fox farm
How much of each nutrient are you using with how much water? *Knowing the brand is very helpful*ppm is kept at 800 have tryed 400-1000 same results
How often are you feeding? (If using soiless) refresh water once a week
How often are you giving nutrients? (If using soiless) " "
If flowering, when did you switch over to using Bloom nutrients?
What order are you mixing your nutrients? (example: veg nutes 1st, bloom 2nd ect)
What is the TDS/EC/PPM you are using
What is the pH of the "Tank"? 5.8
How often are you testing your pH/PPM/EC/TDS? daily
Are you sure your calibration is correct on your equipment? yes
When was your last watering? 3-4 days
What is your water temps? 68
When was your last feeding change? (ie. grow-bloom-micro-additional) 3-4 days
How often do you clean your system: example: Flush out water replace with clean water and nutrients? once a week
What size bulb are you using? 250 watts of LED
How old is the bulbs you are using?
What is the distance to the canopy? my plants are all over the place i keep the lights about 8 inches away from the big plants. i have moverd the lights around to be a few inches away from the small ones but they still didnt grow
What is your RH Factor(Relative Humidity)? low
What is the canopy temperature? 75
What is the Day/Night Temp? (Include flucutaion range) 75
What is the current Air Flow? (cfm etc.) low ventilation jus an open window
Tell us about your ventilation, intake exhaust and when its running and not running ? ocilating fan in grow room plus a couple other fans
Is the fan blowing directly at plants?
Is your water HARD or SOFT? 140 ppm tap water
What water are you using? Reverse Osmosis (RO)? Tap? Bottled? Well water? Distilled? Mineral Water?
If using tap water, what is the ppm/EC/TDS of the water right out of the tap?
If using RO,Distilled,mineral water, what is the ppm/EC/TDS without any additives?
Are you using water from a water softener?
Has plant been recently pruned, cloned off of or pinched
Have any pest chemicals been used? If so, What and When?
Are plant's infected with pest's used to have pest problem hot shot pest strip in grow room

only the one big plant seems to grow and it grows slow. i have tryed every thing. high res temps low res temps high fert low fert high ph low ph nothing seems to change they still grow super slow???