Yellowing leave

@GrowingGrannie Watering before last one I did organic seaweed and sensizyme only and did a small flush with that, last watering was for 3L of water : AN micro 1ml bloom 3ml bigbuds 1ml terpinator 3ml carboload 1ml 0.6ml calmag xtra Runoff ph above 6 and ppm around 200

Without a diary, it's really hard to say but I think you've got two possibilities... a calcium deficiency or a normal "I'm getting tired and heading towards the end of my life." Check the ph of your runoff... if it is between 6.0 and 6.5, your plant is simply at the end stage of life... if it's out of that range, you've got a deficiency that is caused BY that out-of-range PH... do a flush and get the PH back in balance... micronutrients cannot be absorbed by the plant if the PH is either too high or too low... Good luck (and start a diary so we will have all the info needed if you have another problem/question!)

Phosphorous and/or potassium deficiency. Add a P/K booster to your plants diet, your plant likes lots of both when flowering.