Please help, check out pic

Hi amigos.
Here is a pic from a few mins ago.. Obviously it's LED light but you can see the spots plus tips are burnt. I've given extra Potassium for flowering stage. Then I thought, hmm too much maybe. So I haven't given anymore since last week. Yesterday she got added magnesium and sulfur. Too early to tell if that has helped. Next I'm thinking calcium and trace elements, especially copper.
All the ladies are in a coco soil mix, can't be flushed due to location under house, and are 45 days into flower.
Any Help greatly appreciated!
Peace

coco/soil mix should be fed like its soil but im a noob too. I switched to all coco/perlite. I need to feed more often but i have had better results... Less nute burn ect. I noticed that there was signs of burning even when i hadnt fed them in a week... Def ph issue.. Check your pen for accuracy. Plus the ph for coco and the ph for soil are different. What do you ph them at? Coco for me is 5.8-6. Soil i did higher.

Thanks for the reply,
I had been pH-ing at around 5.5-6.5 the whole way but now I'm thinking it was too low because I had soil in there too. I might lay off all nutrients as I think they're present but locked out. I'm going to water at 7 to try and get balance back. Cheers man.