Auto Northern Lights in coco/perl

For those reading - this is my first grow ever and it is mostly for my personal use - it's gonna be lengthy. All comments are welcome though. Day 1 - Gently removed helmet from the seedling but one of the cotyledons has some placenta stuck on it. I left it like that. Also, I sprayed some water around (should not have done that I'm pretty sure) but not much, maybe 50ml (a shot glass worth). 5h later I was wondering why it's not growing at all so I sprayed some more water (I think I pHed it to ~6.3 and it had ~200ec from the filter). I also re-adjusted the light to 76cm. Plant is ~ 1.5cm tall (0.6 inches). Well...8.5h later - as a new grower and being impatient af, I was wondering again why this plant isn't growing so... I sprayed it with some water again (my initial thought was that I'm going to grow in coco and not soil since I've read that you can't overwater a good coco/perl mix. So assuming 60/40 or 50/50 coco/perl has good aeration and won't hold that much water I can just water freely - hopefully this helps some rookies looking through this as well). About an hour later I decided to check the water I have been spraying, if the ec/ph changed at all (I just assumed it could change but not by much). To my surprise, the water came out at 230ec and 6.8pH! So this got me stressin' and I mixed a new batch of water at 5.7pH 230ec. Lesson learned - use fresh stuff since the water ph can shift drastically rather quickly. Day 2 - tent temp and RH in the morning - 21.8 (71F) & 62%. Plant height is ~ 2cm (0.8 inches). Mid day I re-adjusted the water to 5.85 pH and sprayed a bit around the plant. By evening time temp was @ 23.5 (74F), RH 68%. This is the first day I'll turn the lights off for 6h and will have it running 18/6 from now on. Day 3 - morning time temp 22.5 (72.5F), RH 67%. Water pH increased to 6.3 over night and so I lowered it to 5.65 and wet the medium. Seedling is ~ 2.5cm tall (1 inch). I was wondering why it's growing so slow and 2.5h later I re-sprayed around the plant with GHE's Tri-Part @ 5.96pH and 346ec. Leaves are ~ 1cm wide. (0.4 inches). At this point I was begging to think that I'm overwatering since it looks stunted. Temps and RH stayed around 23C and 64% this day. Day 4 - Seedling is close to 3cm tall (1.2 inches). Tent temp and RH @ 23.5C (74F) and 50%. Top of the medium looks a bit dry and light color, will feed with GHE Trio @ 354ec, 5.74pH. Used around 300ml water around the plant. The medium is still moist below after sticking my finger in it. Seedling has not grown from previous day. Increased light distance by 3-5 cm (1-2 inches). By the evening temps and RH were 23.5C (74F) and 63%. Day 5 - morning temp 25.7C (78F) RH 38% (accidentally left the heater on through the night). Fed cal + mag at 3:2 ratio (Canna mono Ca & Canna mono Mg) (12% Ca % 7% Mg separately in bottles). Solution ended up being 430ec and 5.7pH. Increased light intensity to 40% at 76cm (30 inches) from the plant. The leaves don't seem so droopy anymore, they're pretty straight at this point. At this point I was thinking that I'm still overwatering since the medium just below the surface is still rather damp. Temps and RH were around 23.4C (74F) and 64% for the day. Day 6 - morning temp 23.8C (75F) and 55% RH. The plant is stuck at 3cm in height (1.2 inches) but the leaves grown to 2cm wide. I'm not going to give it any water today even though the top of the medium looks dry. Will give it water tomorrow morning and see what happens. Increased light duration to 20/4 to keep the temperature from fluctuating between when the lights are on and off. Day 7 - temp 23.2C (74F), RH = 54. Nothing has changed. Gave it 50ml of distilled water @ 6.1 pH.