I think you may have too many wild ingredients going on. I would suggest starting new plants in small pots with fresh potting soil out of the bag. Transplant when they outgrow the container, And then not add anything except fresh (if possible ph'd) water and maybe get a good blooming liquid nutrient when it's time. And your right that SecretGarden's lighting setup would be a good idea, from what I've seen in his log he's gotten great results that.