hey man, thanks for a quick reply.
Are you sure that is light burn? I raised the light to the top (as high as it will go) when I first noticed the problem, and its not 35cm away from the top of the plants.
I just mad some fan adjustments so its flowing RIGHT in between the light and plants, but I don't think it's just down to heat. Check out the last picture, deffinatly not light burn.