Apple Blossom/Nap Time in 2x4

I started week 2 by moving the Jiffy pots to prepared coco. We lost our first two contestants, as I decided to only prepare containers of coco for the best 4 seedlings. 3 Apple Blossoms and 1 Nap Time. I soaked the coco in feeding solution diluted to 450 EC (measured in microsiemans), which is what the first watering will be. Ph is about 6.0-6.1. Waterings began 24 hours later with incremental increases in the EC strength of the solution (chart below) each time, by 50 to 75. I have two small fans in the tent. A 4" up high directed at the driver of the LED and an 8" on the floor pointed away from the seedlings so there's some movement of the seedlings but they're not blowing around heavily. Temps are on the cool side. It can get down to 70 during the day when my house heat isn't running as much, and tops out around 74-75 at night. I've begun running a space heater outside the tent at times but I'd like to avoid it as much as possible. With this my fist grow, I was wondering if I'd be paranoid about signs of problems and maybe be too quick to jump to treatments of problems that don't really exist. So I'm trying to be patient and relax. But it does seem that at the end of week 2 I may be having an issue. 2 of the 4 seedlings are displaying some slight curling and twisting. Very slight, but seems to be progressing. I've heard that this can be a sign of CalMag deficiency in coco grows, but I've also heard that some growers are too quick to make that assumption. I didn't want to wait for discoloration to confirm there's a problem so the last 2 days of the week I began to apply a light foliar spray a couple times a day. I mist all 4 seedlings but the two showing twisting get a little more. I turn the light off for a few hours or drastically reduce it for 20 mins after applying foliar CalMag. The 2 seedlings with twisting were the two in the middle of the setup, so light intensity could be an issue. I swapped them with outer ones and slightly reduced intensity of the light to about 30%, hung at about 20". Other potential causes could be the lower than desired temps, an overwatering/root oxygenation issue since I'm in plastic containers and don't have a feel for watering yet, or a coco issue. A clue could be that the runoff EC has been consistently much lower than the inflow EC. I used prebuffered coco that I tested and then presoaked at the same dilution of my first watering. I don't think I'm overwatering and when I do water, it always has nutrients in it. I water slowly to 10-20% runoff. By the end of week 2, all 4 are showing a root out of the bottom, and all are working on their 3rd node. It just seems like things are running little slow. EC chart (in microsiemans per cm3) Inflow/Runoff 444/485, 474/435, 563/410, 612/390, 689/395, 755/410, 817/410, 895/450, 974/485, 1050/510, 1014/565, 1029/600