Help Plz! 1st Grow - something not right! :(

...just adding the extra images - TIA ladies and gents...(sorry images are in a bit of a mangled order)

you need to vary your PH between 5.8 - 6.3 a couple of times a week or you will lock out MG
your plants also look over watered and or overfed (too much N) hard to tell under that purple light
just noticed your feeding them at an EC of 2.5, at that stage of growth i dont go over 1.5 EC

shut off your led's and take pics

and you better get those spider mites under control NOW because they are super hard to get rid of

Sorry people; apologies for purple pictures but thanks for coming back to me! Please find attached images in regular light.

- Spider Mites have not been seen since. There were only four or five that I found on a single plant but I blasted all 57 plants with some Margaret Roberts Organic Insecticide. I stank like garlic for hours but it seems to have worked.
- Vary the pH - yes I will definitely go all the way up to 6.3 for future feeds and vary accordingly. I did look at some chart about pH and Nutrient Uptake, I thought I would be okay. Thanks.

Images from tent 1 on this reply, images from tent 2 on the next. All were started at the same time, I just sorted the better ones at the last re-pot into different tents for hopeful canopy uniformity.

Images from Tent 2 (generally a lot better but still not all great!)

- So the EC of 2.5 was a bit of a trial. I thought things looked deficient in Magnesium....and I thought I must be doing the EC wrong....so I took the EC reading out of the tap as 0.16, added Epsom Salts as per these forums (which took my overall EC to exactly 1.0), then i thought I still need to add nutes...and the packet says I should do 1.5 EC.....so I thought fine, I'll add 1.5 EC worth of nutes....hence final EC was 2.5....schoolboy error?

Many thanks for taking the time to have a look into my somewhat bungled attempt at proper gardening

when you give your plants MG ph on the high side you can also folia feed the mg, we all make schoolboy errors the trick is not to make them twice lol

Wow, thats all info from your very first grow? wholy moly!!
Im also on my first grow my set up is simple by comparison. I have 3 hps 1000watt 3 can fans 2 6" intakes with filters and 1 8" out take with a 24"charcoal filter. 3 osilating fans a humidifier and air purifier. Using a small propane heater running during the light 12 for co2 (only pilot is on) and only run purifier during the dark 12. thats about it. My rh depends on whats going on in the room as far as whats happening with the girls, same with the heat. Right now im fighting pm so the heat was up to 82f while i dropped the rh down to 20% to be sure the potassium bicarbonate solution has a chance to dry out of the buds after about 8 hours at that ill be bringing it back to 72f during the light and 62f during the dark and ill bring my rh back to 35%to 40% till the last couple weeks then ill drop the rh to 25% and my temps i will drop roughly 8-10 degrees to allow the buds to tighten and start ti over produce resin.
thats the plan anyway here they are beginning week 5

You're doing way too much for a first grow, you need to take a step back and just let the plants grow. You are over thinking this, that's a ton of info and plants to try and control/calculate.

Understood Mr. CaliSmokes however it's a little late now

Someone has privately asked if I have root aphids. I have checked for these but am not 100% sure of the signs. I HAVE however noticed a small handful of what I believe to be fungus gnats.

- What's the best way to spot and/or identify the difference between fungus gnats and root aphids? (I read that one is a small problem, the other is a monster problem)
- When I treat for either of the above, can I add treatment to my nutes so as to feed and eradicate at the same time?
- No other thoughts on the yellowing and/or slow growth on 50% of the plants?
- BobTokes, I will definitely try an Mg foliar feed at a higher pH. Thanks for that.

Okay, thanks anyway gents. I took some plants apart - I do not have root aphids, I do not have root rot, I do not have spider mites. I have a small handful of fungus gnats. I also have incredibly slow root growth in 50% of the pots.....because all of those pots are too wet.

.....I had someone trustworthy over today and it's simply a case of over-watered (+ over-fed as I falsely diagnosed initially). I weighed each and every pot - ALL the poor performers weigh in at 4.5 - 4.7kgs / 10lbs (last watered Xmas morning). All the top performers weigh substantially less. The best visible plants weighed in at between 2.6kgs / 5.75lbs to 3.4kgs / 7.50lbs.

Unsure why SO many people say 'you cannot over-water coco' or 'water every other day' or '5 times a day' or whatever. This is terrible advice in my rookie opinion. Anyhow, I'm looking forward to the poor performers catching up, fingers crossed!!

If anyone has advice on how to dry out my other 4.7kg / 10.4lb pots more quickly I'd be really grateful. I need those roots to start hunting!!! Big thanks and shout out to those who tried to help.