Some input please! Feedback NEEDED

Hey-
Im a somewhat experienced grower, have had a lot of luck in the past, and am trying to do a medical grow similar to some smaller ones I've had in the past, just with more light. Currently running 2 1000w HPS, fully vented so heat is not an issue, using organic soil and organic nutrients. Soil choice wasn't ideal, using Miracle Grow Organic Choice, really wanted FF OF but what am I gonna do? Nutes are Fox Farm, Big Bloom used for first week, now using lighter amounts of Grow Big in combination with the Big Bloom, and of course have my Tiger Bloom for the best part of the grow. Most of the room looks great, big, quick, vigorous growth. This is one of the first grows that I've gone entirely from clone, not a single seed grown plant in there. Half of the clones came in soil, the other half were in some sort of gray cubed hydro medium. At first, the soil clones seemed to have an obvious edge over the cubed clones, I eventually took a few of the cubed clones out of the soil and realized the roots were having a hard time getting through the cube so I opened the cubes carefully and re-planted, big success. The rest of the cubed clones just power housed through these hard times and are now the biggest clones in the room. Overall, the only issue with the Miracle Grow Organic is the gnats, luckily my good friend neem oil is kicking ass and taking names. The first two-three days I was overwatering slightly, didn't realize how good the water retention was of the current setup, but I have been giving them significantly less water and things are looking good. As of yesterday, a few of the smaller plants started yellowing on the lower leaves, and the leaves are now curling downwards. I've looked at all the picture guides to plant problems and cant find one that matches up with my problem. A couple of them are actually yellowing slightly yet showing signs of over fert at the same time? And as of earlier today there is one plant that is noticably yellow from head to trunk, only the veins continue to show a beautiful green. All the plants that are displaying problems are somewhat wilty, and a few of them have purple/red stem action going on. Like I said, I am not new to the cannabis cultivation scene, but I'm relatively baffled. Do you think the roots are having a hard time getting into the soil? Could I have packed the soil down too hard? Am I over fertilizing? Am I under fertilizing? Im only giving them 2-3tsp/gal of grow big as of two days ago which marked their 2 week anniversary of growth. Im wondering how these few trouble makers are giving me some problems while the big guys (gals) are lush, green, branching, and beautiful? There are a couple of the big gals that are still green and beautiful, yet a few of the larger/lower fan leaves are curling under. Any input is much appreciated, two heads are better than one and so on... Thanks in advance!
-Rade

I donâ??t know what stage of grow Ur at but I'll tell you what I have experienced. There have been only two times I have ever seen yellowing of leaves 1st lack of nitrogen, which I have come across in my last two grows which I have put that down using different nut's this time and 2nd the plant is coming to its end of its life. The second is where I see the most of what you describe when u say a couple of them are actually yellowing slightly yet showing signs of over fert at the same time but this usually happens around 8th week of flowering but I have also had it happen to me when I had to flush some plants at least thatâ??s what happened to me. Or maybe it could just be that these plants have bad genetics, just didnâ??t root well or wasnâ??t a good clone at time of cutting also it can take a while for the plant to sort its self out depending on how bad she is. I donâ??t claim to be an expert man but when things go wrong and they always do for me with nearly every grow I go back to the start and stop everything, just feed water and watch them like a hawk, If things get better you know u overfeed them if they get worse then it could be the water or soil if things stay the same then thereâ??s something missing like I said yellowing can = a nitrogen problem, but thatâ??s what makes growing interesting although ur probably cursing all that crap right now :) I have purple/red stems on most plants I grow and donâ??t know why but thereâ??s never been anything wrong with the bud but like I said no expert just thought I'd chirp up seeing as no one else wishes to say anything plus nothing else to do OJ man, hope u get Ur problem sorted

First off, best not to feed your plants until they are 2 weeks old. So over fertilization is the likely culprit. But just to cover basics - you have a pH pen right? Use it every time, even if you've pHed a batch of water in advance. I suggest you flush the plants and leave them set for a week before you do anything else. Any corrective measure needs at least a week before you can tell if it's been effective. A rule of thumb is to start ferts at 1/4 strength @ 2 / 3 weeks. I go with 1/8 strength and increase from there. It's easy to add more but not so easy to take it back. Also, don't be tempted try lots of things. People always want to throw chemicals at their plants with the idea that if a little is good then more must be better, right? Wrong. So flush them and leave them alone. Finally, pictures, and strain information always helps. Oh just re-read. The MG soils are notorious for been too hot, especially for seedlings. Hope this helps.