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First grow and not sure if I have deficiencies

Hello everyone
I'm a new grower this is my first grow, I'm growing 9 critical impact seeds from vision seeds and a random free seed that is apparently 'cherry amnesia'. I have germinate my seeds with success and they have been growing in 100% canna coco. I've been feeding them canna nutes (canna start, rhizotonic) starting from a quarter strength working up to full strength today which is day 16 from germination. I have them under 2 600 watt MH lights and have an oscillating fan on them to aid there stems to grow strong. I am pleased with how fast they are growing but for the past few days I've been noticing somethings that I'm not sure on. The first thing is I seem to have a kind of white looking vein through the middle of all my leaves and when I've tried to research it some places say it's fine some say I need cal mag... if anyone knows what this is a bit of help would be excellent. The second thing on my so called 'cherry amnesia' I am getting a weird kind of leaf curling that I can't seem to explain where the fingers overlap. It's not from heat stress as my temps are always under 28. Could it be a deficiency or just the strain. I have pictures that I can upload when I figure out how to do it as I'm also new to the forum as well as growing. If anyone could help me out I'd be much appreciative. Also help uploading the pictures would be good too.
Thank you for taking the time to read this.

The top image is my cherry amnesia with the curling leaf problem
The next two are my white vein problem
The last picture is what they look like in general
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