lime green spots - AI, OG, VK, Bubb76 Coco grow

Hi this is my second coco grow, had issues my first time around(did not do DTW, learned my lesson), in the end I would of gotten ~8 ounces under 600w if it weren't for all the seeds, as I didn't throw the males out soon enough. Couldn't grow during the summer, got way too hot and didn't have proper ventilation in the room, which would of caused high temps in the tent, fixed that issue now.

3 Aurora Indica (Nirvana seeds), 1 Violator kush (Barney's Farm), 1 OG Kush (Reserva Privada)(Freebie), 1 Bubba 76(Emerald Triangle)(freebie).
Using House and Garden nutes, Coco A+B, Roots excel, magic green Foliar spray once a week. No other additives until flowering (Bud-XL, Top Booster) (According to personal research H&G produces very high quality buds without losing much in yield)
PH 5.6-5.8 (Nutradip meter that gets calibrated every 2 weeks)
Started with 4' t12, plant and aquarium bulbs, just let the plant grow into the lights. Now under a 600w MH after 3 weeks of growth of AI. Light is ~16" above the top of the canopy.
Started at 24h light, now down to 20/4, will drop to 18/6 in a week or two to save on power.
4x4 Mylar tent bought on ebay.
Fan inside tent, on high, but not blowing directly on plants.
6" 400CFM fan that's always on Also bought on ebay.
Bagged Coco
Started in 4" pots, watered once a week to get a solid root ball started before transplanting into 2 gallon smart pots
Tempts are roughly 70-75F with the MH with RH ~40%


First week; just straight PH'd water, Second week; 1/2 Seedling strength according to their chart, 3rd week; full seedling strength

The Aurora Indicas(2g smart pots) are at just over 3 weeks, VK/OGK(4" pots) just over 2 weeks, and Bubba 76 (in the cup) just under 2 weeks.

Ignore the brown spots on the plants it's leftover from foliar spraying, misted too much/too strong of a mix just under the recommended 10ml per liter, about a day ago before lights off. The issue I'm having right now is that one of the AI plants has Light/lime green spots, which was noticed before transplant. During transplant, the leaves shot straight up, as if given a dose of viagra, so it is healthy. Here are some pics. Any advice? Mag def, thrips, other?
 

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Anyone know what the whitish color on the leaf is, most noticeable on the top left leaf? Or why it's slightly curling? If I had to guess I'd say it prefers a It's Violator Kush
DSC02431.jpg

Growth has also been slowed, as this plant was ahead of the OG Kush and Bubba 76 (Both on the right) VK is bottom middle.
DSC02426.jpg
 
I was thinking if you're not overwatering, I'd test your water runoff to see what it's PH is to insure there isn't some sort of problem with your soil. That's about the only suggestion I can give.
 
I water them twice a week right now, and they're in straight coco. EC 1.3-1.4 5.8PH, meter was calibrated a week ago, PH was off by .2 or .3.

Fed my plants yesterday, and today I decided to semi-flush the VK, first drops of runoff were 1EC and 6PH, watered enough to drop it to 5.9 and .8EC (tap water is .33EC). I water with ~70F water, comes out at 60-63F. Maybe I just happened to get a dud pheno, does that happen?
 
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