Thanks for the input, much appreciated! My nutes and soil are all from the same company and line (plant magic old timer) apart from the calmag I started adding when I saw problems and they are specifically for MJ as far as I know, although I suspect I could be using some pretty old stuff. The calmag seems to have made no difference or could have even made it worse, it's hard to tell. I've been following plant magic's schedule for photos which I reduced slightly for a autoflower time period. I probably should have mentioned somewhere I am using aerated water via a fish tank pump. Thanks for the heads up on liebig, I'll have a read in bed!