Yellow tips- should I start feeding or just water and calmag

Hey everyone, I’m a first time grower and I’m starting to get yellow tips on my 4 white widow plants. My ph is 6.5 well water, I’m using ffof that I transplanted into 17 days ago and I haven’t fed them any nutrients just water. I’m running 4 Carambola 1000 that are 120w each at 20" above the canopy, so I’m ruling out light burn. I mixed 1 gallon of water with 1 tbsp of calmag last night and watered the 4 because I’ve read that others add a tbsp of calmag every watering and feeding. These started out slow because of my novice mistakes so this is in week 5 of veg. Basically, should I start feeding a half dose of the FF trio as instructed on the feeding schedule or just water and calmag? Thank you for any advice.IMG_20210502_154352835_HDR|666x500

Do you have a tds/ec meter to measure your ppm? Ocean usually feeds plenty for the first 6? Weeks I think. If you monitor your run off ppms, begin feeding when run off drops below 800. Did you adjust ph after adding calmag? Also don’t need calmag with well water. Might be getting a slight burn with calmag this early OF soil. Tips would appear orange, just return to monitored ph water. Pictures help.

I do but I didn’t check my run off, I water in 2 days so I’ll check it then. Thank you @Budz