Curling leaves, slightly yellow. Suggestions

Plants are still really young but I'm noticing the leaves are curling slightly.
They're Northern lights autoflower from Royal seeds
Currently on basic canna A+B in Coco under 150w QB led.
No additional nutes yet as planning on kinda letting the plants tell me what they need like this and build them up instead of down to help learn to read the plants instead of just reading labels.

Picture attached shows it best.

Lighting schedule hasnt been the most consistent due to faulty timer plugs, minimum 18 hours of light with a few 24h days and 1 12/12 right at the start when they were seedlings, set to 18/6 now though.

Water is Ph'd at 5.8-6.2 watering once top inch of Coco seems dry (4 shot glasses per plant roughly 2 times a day)
Canna A+B at 1/4 strength
Light is a currently 150w ts1000 Marshhydro at 23"
5gal fabric pots
Intake fan running pretty much 24/7 unless tent is opened up fully


Have read it could be an issue with nitrogen, calcium, too much water, light or wind burn?

So let me know your suggestions and I'll get whatever needs adjusting or ordered adjusted and ordered!

thanks

Forgot to mention I have been gently bending the leaves down slightly as they've grown to train them a little with minimum stress and open the plant up from young.

It's the natural curl on the 1st set of fingers that caught my attention

My guess would be calcium deficiency. Are you using RO water?

Here's a Green Crack seedling that popped 12 days ago. I''m using RO water & put the wrong dose of Cal-Mag in. Notice the brown spots, leaves gnarling in the middle & tips, leaf edges rounded, the ruffled appearance on the large leaf, stem so short that the large leaves are covering where a new node should be.



Here it is 24 hours after correcting the nutrients. Significant growth achieved. It seems to have "expanded", less ruffled appearance, sharper tips around the edge of leaf, the stem of the large leaves has started, the veins are much more delineated. The gnarled leaves will remain gnarled but new growth will be healthy looking.

Nah straight tap water with the pH adjusted. Waiting on a new EC meter
Will add some cal mag to the basket