'praying for magnesium' is a myth. Leaf edges curling up is a classic symptom of heat stress. Magnesium looks like regular, pale stripes between veins.

Why did you use epsom salts on your plants? And it looks like yo used a LOT... those leaves have salt buildup on them. You need to spray them down with CLEAN WATER, avoiding letting any get in the res, or do it immediately before a scheduled res change.

Do your roots appear white or brown?

Your ppms are on the high side; bring them back down to 800 or so and work back up.

Get your temperatures at the canopy down below 85'F TOPS.