Chow_13answered grow question 2 years ago to much food causing lockout. The leaf end curling down like that is nitrogen toxicity. and the inter veignal chlorides is a Magnesium deficiency caused by a lockout( to much food)
Plagron Royalmix has 6-8 weeks of food in it. And your feeding twice a week. Stick with just water for another few feedings.
Fully saturate the soil and let it dry to 2" below the surface before watering again. Your schedule should be water,water,feed,water,water,feed.
I see you have EC/PPM listed. Test your EC going in when you water, Collect the runoff and test the EC coming out. They should be close to the same. If not then adjust.(
In=Higher, Out = Lower - increase EC if the EC going out is higher then reduce your feed. or water only until it gets back to normal levels( could be salt buildup )
Good luck and Happy Growing.