Northern Lights Dying

Ok, so as I was filling out the troubleshooting form I think I may have stumbled upon my problem, but would still value any 2nd opinions on my remedy and maybe this could help someone else too.

E-indoor or outdoor: Greenhouse added on to back of house
E-soil, soilless, coco, aero, or hydroponic: Soil
CSL-Soil type/brand: Miracle-Gro Organic Choice Garden Soil, Miracle-Gro Organic Choice Garden Soil - Scotts Miracle-Gro
SCLR-Soil or slab runoff pH: 6.4ph runoff
E-Water source: 24hr city tap water, ph'd down from 7.0 to 6.5ph
E-Source water pHL: 7.0 ph'd down to 6.5ph
E-Age of plant: 3 1/2 months
E-Type of fertilizer: None for a week, then 3tsp Fox Farms Grow Big 6-4-4 & 2tbl Big Bloom per gallon h20
E-Rate of application: Once last week
E-Lighting source and distance from plant: 20-22" from 1000w hps and a 400w mh
E-Air temperature (both day and night if you are running a dark period): about 75F day and 65F night
E-Air % Relative humidity: unknown inside greenhouse, however weather websites say its in low 90's outside
E-Lighting schedule: 24hr
E-Type of ventilation your room has: 2 fans to circulate air around greenhouse always on

I inherited this northern lights in a 1 gallon soil pot and its leaves were yellowing, drying up, and falling off. I transplanted it from the unknown soil to a new 3 gallon of miracle-gro organic choice garden soil due to it's nutrient content of .1-.05-.1 so that I could flush it with 24hr city tap water that had been ph'd to 6.5, after not seeing much reaction about 10 days later I was worried it was possibly deficient in something so fed it some Fox Farms Grow Big 6-4-4 and Big Bloom at the above dosages when watering. Now about a week later after 2 feedings with the nutrients it has only gotten worse. The plant was already very slender and lanky when I got it and had very small and pale green/yellow leaves. Now even the newest growth can be seen turning both yellow from the tip down and curling downward while at the same time a rusty purple or reddish color can be seen until the leaf dies up and falls off.
Upon looking up the soil information I used to fill out this form I realized the product description page made it apparent that it should not be used in a container as it will suffocate the roots, it is meant to be mixed in with the top of native ground soil. So today I transplanted it into a 2 gallon pot of Black Magic Potting Soil and thoroughly wetted it with 24hr tap @ 6.5ph and plan on using only water for a week or so to see how it responds to the transplant. Also, I did note when putting it in the new soil there was not much of a root mass and it hadn't really branched outward, so this may give some evidence of that outdoor soil restricting the roots.
If anyone has any question or comments I'd love some feedback on my diagnosis and treatment and if there's anything you would have done differently or if you think it's something else completely different causing my problem then please speak up so that others can learn from my mistake as well. I really hope it pulls through, I've heard good things about the resilience of the northern lights strain, so I'll follow it closely and keep updates and pictures coming. Thanks
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I think that too much fertilizer. I doubt if that kind of potting soil needs anything added to it, except for mabey a single shot of P in the first week of flowering. Is the white bucket a DWC?

So should I have kept it in the soil that said not for use in containers and just kept giving it straight water? Or are you referring to the new soil and I should just stick with the water w/ no nutrients added at all? The white bucket is a DIY that was thrown together, it has a submerged water pump set to run 15min every hour, it pumps up some plastic tubing to a ring made of garden hose with holes aimed at the bucket of hydroton rocks. There is actually 2 diff plants in there with roots suspended in about 2-3 gallons of water around 5.9ph w/ fox farms grow big hydro 3-2-6 @ 3tsp per gallon. I don't have an airstone in it because the spraying action from the pump seems to keep it oxygenated enough.
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Those brown patches, were they first a golden-yellow color? If so, then I think you have bad magnesium deficiency in the soil grow. Check the contents of the fert you've added and the contents of the bag of soil if you still have it, and see if there is any mg and calcium in those. If not and the spotting started off as gold yellow, you might consider going to a hydro shop and getting some calmag and give one shot of the recommended dose on the bottle and see what happens. It's kind of expensive to do that and you'd like to think that the ferts you have already have enough in them to make plants grow, but that's not always the case. It looks like you're doing great with the hydro bucket but you're getting a little leaf tip burn, which means that you're over-ferting some. Could be because the time you run the pump is too often, or could be because you're using too much fert in the water. Perhaps try backing off a little on how much fert is in the water and see what happens. Since you have a good hydro bucket, stick with it and build another if you want to grow again. Soil is a good way to grow, but go with what works. You're right about the spraying action putting enough oxygen in the water. It's all you need and them some. This method is so good infact that it might be the reason why you're getting leaf tip burn and the solution is to reduce the fert content some as more oxygen make nutrient take up more active, so you don't need so much. Good job on the hydro bucket.

Thank you for your help, but unfortunately the sick northern lights is no more. While doing some work to the greenhouse this afternoon two of the northern lights were moved outside in the sun to make moving around in the greenhouse easier. During no more then an hour of being out there the sick one was taken. I'd rather that the sick one was taken than the healthy re-veg, but still it sucks after the time and energy put into it. Anyway I'm going to focus my efforts on all the other plants now that it's out of the picture. And to answer your questions, the soils didn't have any Ca or Mg (or at least no mention of it on the label). The fert was FF Grow Big 6-4-4 which has .6%Mg and no Ca, i used the heavy feeding dose of 3tsp per gallon. I do have a pretty full bottle of Calmag laying around. Yes the Hydro is doing excellent, although I ended up taking over the duties of caring for 2 soil plants and that bucket, I feel like I just do better with that setup then with dirt (but I may just feel that way because it's doing the best on it's own). I'll try dialing back the fert in the bucket this sunday when i clean it out. Now that I'm a plant under my limit I'm planning on making another bucket. Thanks again.