Help! first grow, babies are sick PICS

[marcogonzalez82]

Closet vegetating clones: In all, I have 3 sour diesel x OG kush clones, 4 OG kush clones, 4 blackberry bubba kush clones, and 2 cherry ak47 clones in hydroponics setup. I received the rooted clones about 5 days ago from a dispen. They have been transferred into hydroton medium in nursery pots. All these clones have been under Hydrofarm T5 2ft 4bulb on 18/6 cycle. (Maybe not enough light, so I'm planning to transfer some to 400w mh tent. Need a second opinion on this.) For every 5 gallons of purified water with ppm of roughly 150, I have added diluted nutrients of half strength Super Nutrients SVA (1.5-0-2.6), Super Nutrients SVB (.5-.5-5.0), technaflora MagiCal for magnesium, calcium, and iron, and Grotek Monster Grow (12-7-15). Planning to change my reservoir's water to RO water of 5ppm within a few days.
Reservoir ppm is roughly 750 ppm (too high?)
Temperature = 70
Humidity = 42%
Pumped 3 times a day 20 minutes each time for a total of 1 hr. (too little?)
I know, my setup is not perfect and am open to suggestions which will be very helpful.

In the pictures I have uploaded, my sick Og kush clones are turning blueish gray in the stem area and spreading throughout plant reaching into the nodes. My sour diesel x OG kush clones are also showing blueish gray color in the stem area spreading throughout the plant. The cherry Ak47 has yellowing leaves on the tips and also show blueish gray color in the steam area.

Is it because it needs more phosphorus? Am i missing essential nutrients in my feeding? Please help my babies!

[marcogonzalez82]

additional pics attached

[marcogonzalez82]

ph level around 5.8-6.0