First time coco grow

I would recalibrate your pH pen...

That's a safe EC range.. still have to react to plant but you can be patient and more certain of the diagnosis before acting. Things will stand out as you find more plants need a little more Mg.. or not with experience and observance. So, runoff is a bit of an average of what you add and previous state of substrate. If it's higher on runoff, it's potentially a bit higher before you added an acidic solution. pH rising could be what is in the substrate - sometimes it's not the pH they advertise. Another possibility - You are adding citric acid.. is this also adding sugar? this would be feeding microbes that could impact pH. Try using 5% acetic acid (white distilled vinegar) to pH down... won't need more than a couple mL per gallon. The nutes used may not be well-stabilized (buffered). Even at 7, everything should* be fine or manageable. You don't want it going much higher though and better to lower it a bit. So, becareful of adding more acdic feed. Maybe try one @ 5.5pH and check runoff. It is a logrithmic scale from 7 so a little is a lot relative to changing "7ish" and you don't want any normally impossible reaction caused by an unusually acidic pH. Check runoff - try to do at same point as before. All the nutes are still avaialble to the plant @ 7ish. Iron / manganese might be the first to show signs of deficiency (fwiw, both result in interveinal chlorosis, tho progressing from opposite ends of plant and maganese will get necrotic spots.)

If you are starting with water at 8 or 9 pH, you have a big problem. Adjusting your pH with acetic acid (vinegar) does not work to stabilize pH levels long term and I believe a "pH down" additive based on phosphoric acid will keep pH stable for much longer. Also make sure to adjust your pH last, after all the fertilizers are added to the water. At this stage you will have to flush heavily with pH adjusted water (containing phosphoric acid) until your run off reads 5.8.

The problem again lies in your pH.... it's far too low for the essential nutrients to be absorbed by your plant. 6.2 is absolutely ideal but if you can get it between 6.0 and 6.5 you'll be fine.... I see you're giving her calmag - plant can't get at what you're giving her... get the pH up! Good luck!

I think they are shocked from light change,or light is close to plant try to download an application to see how many light you giving

I think its all caused by light stress. Plant is having issues with nutrients because the light is to strong. Raise it up to 50 cm and keep your feed as is. The small twisty growth at the bud sites and the serrated edges curling up are both signs of heat/light stress. Happy Growing.