First time grower needing advice

This is my alien rock Krishna as of today
I am wondering what has made the leave start to claw and slightly turn yellow I have two other plants crem sickle og also showing signs not as bad and krunk juice showing the least amount of signs. I don’t want to mess with my plants to much so I’ve chosen to not take pics of all of them at the time of writing the post. Below I will be doing my best to post all the information I can also here were my plants Wednesday 2 days before it started.

I watered Thursday here is that information

Taken from my of and I journal and then this is friday

This is the current ppm and ec honestly I don’t really understand these I think

ec is twice ppm…