I run Mega Crop too. Youre in flowering, I see potassium deficiences on some leaves. There have been reports of P and K deficiencies with only using Mega crop, even at 5grams a gallon. You should have read that thread and did your homework. I would supplement P and K but you lost some yield man. I run in pure coco. What I would do is feed a plant and let the runoff go for about 5 seconds then scoop some up in a small measuring shot glass and use your EC meter to test it. Doing that can give you an idea of what concentrations of salt are in your coco. Its not accurate but its better than firing shots in the dark. Also, never test runoff ph its useless data most often than not. As long as you feed with a solution phd 5.8-6.1 the media should have a stable ph.
Okay looking at your picks and you being in week 6 flower (depending on how long that strain your growing flowers for) they should not be losing their greeness at that stage. So try this... Feed with what you usually feed with and again let the runoff go for 5 seconds and then collect some and EC test it. If the reading is WAY higher than what you put in (say by 300ppms) you need to flush it. Never flush with plain water in coco because that causes osmotic stress in the rootzone and stress in flower (even though deficiencies are a form of stress). Flush with a solution of MC of about 0.4 EC. You have to flush with that until what comes out is close to what you put in (the 0.4 ec). I feel bad for you if you have 2-30 gallon pots because im sure you know the flushing rules LOL. Honestly flush how I told you and then dont feed for one day ( like I said youre in flower so its up to you. Next time learn from you mistakes or lack of being informed). Also Always feed until 10-20% runoff or salts will accumulate in your coco. Dont let the coco even get dry EVER. The coco always has to be moist. So after the flush, let the plants rest a day, then feed what you were feeding and add a P and K supplement bro but at this point like Ive said youve probably lost some yield. Good luck!