New grower questions yellowing leaves

[Farmer_grow]

Light: Omega black 720W (set to 250W)

Environment: 22-24c, 60-70% RH

Medium: Coco canna pro, 30% perlite.

Nutes: Canna Coco A+B, Rizo, canazym, PH down (phosphoric)

Germination method: pre-soak + paper towel, place in medium when root between 1-2cm.

Feed history: pre-watered medium with "light-water" with a starting ppm of 100, then added up to a total of 250ppm with A+B + Rizo, PH 5.8, watered until run off, sprayed lightly once a day, then after 4 days watered until run off with 300ppm same mix + canazym.

question:

some of the leaves are yellowing and drooping, could this be over watering due to the pot size or could it be due to the light water base and a calmag deficiency, or light?

PPFD meter app reads 400-500 but I doubt it's accuracy, there's little information on this light I can find except a single test done at 250W in a non reflective room which measured 480PPFD @ 2foot. My light is hanging around 4 foot above these seedlings.

Worried about adding calmag and adding to any protential overwatering problem, the medium feels damp/moist in the first 2 inches, any advice?

 

[Farmer_grow]

Ahh forgot to add some info

24/0 light cycle

Strains: Kong Kong, banana purple punch, Tropicana cookies, all autos.

These are 10-12 days from seed

 

[Imzzaudae]

#1 rule is do not push the plants!

Your light is to bright.
Set your light at least 30 inches above your seedling tops.
30% power for another 2 weeks.

Then 60% power at 30 inches the rest of the grow.

Set your timer 18-6

Water only when dry!

Don't feed them for another week!
1-2 ml Cal mag pr gallon water will be fine. I does not take much.

 

[Farmer_grow]

#1 rule is do not push the plants!

Your light is to bright.
Set your light at least 30 inches above your seedling tops.
30% power for another 2 weeks.

Then 60% power at 30 inches the rest of the grow.

Set your timer 18-6

Water only when dry!

Don't feed them for another week!
1-2 ml Cal mag pr gallon water will be fine. I does not take much.

Thanks for the quick reply, I have height restrictions so I can't raise the light more than 48 inches above canopy, the lights are on 250W and sitting at max height, is there anything else I can do to reduce their light intake?

My env is hard to keep steady without a 24/0 cycle, I have dips in temp down to 15c.