I woke up to this this morning this is a wost leaf example but 50% have this yellowing any help would be appreciated.
You really do need to give more details, like are you feeding nutes? whats the ph of your water, and also your run off water(the water draining out the holes after a good watering), what type of soil are you using, what type of lights/and how close are they etc.... But from looking at the picture alone, it looks like according to the plant abuse chart either zinc or magnesium def. It says zinc can be locked out by a high ph and also that zinc and magnesium def. usually accompany each other. From my limited exp, i can tell you that epsom salts can cure a mg def at about 1 tsp per gallon of water. But if it is being caused because of a high ph youll need to flush your soil well with distilled water to try and get your ph back in range. Here is the link, after all you know more about your situation then anyone else. Good luck.. http://www.greenmanspage.com/guides/plant_abuse.html
Im using GH Flora nutes micro and gro in non fert organic soil 400 watt hps 24/0 yesterday started with epsom salt hopefully it will help. Ph soil - 6.5-6.8 runoff 6.5 - 6.8