HSO Blue Fire

2nd week of my seedling started with my first issue with this grow. To this day the issue is: very bright green colour of the seedling and stunted vertical growth. First I thought it might be that the light is too close to the seedling. So I hung the light for three days 70cm above the seedling. As I couldn't see any change in colour of the seedling, I hung the light for another three days 80cm above the seedling, but the issue persisted. I have then hanged the light down back to 60cm, as I don't think that the issues were caused by light being to close to the seedling anymore. What I know is that at least one issue was caused by my mistake. While hanging the light 70cm above the seedling, I was also worried it could be the nitrogen deficiency, so I have fed the seedling more than I would normally do. This I believe has caused the stunted growth. What is the cause of the very bright green colour of the seedling remains unknown to me for now.