Auto with rusty leaf tips

I have a ILGM WWA is seven weeks along now and am getting brown/rusty tips to a good portion of my fan leaves. It started has been in flower now for about 2 weeks I believe. I am using FFOF as my grow with a small seed starter center without any nutrients. I am under a viparspecrta 600. Have a carbon filter CO2 bag and two oscillating fans in the grow tent. It’s on a 18-6 light schedule and is watered with dechlorinated tap water that has been phed to 6.8 250 tds. I add cal mag every other watering or so. Soil runoff ph is 6.1 now. My soil has been very acidic but has recently been balancing out. Temp usually stays around 82 at most and rh45 now. Night time is 73 and still around rh45. Filter fan is ran 24/7. About 1 1/2 weeks back I added Gaia green organic fertilizer 3tbs bloom and 1tbs general purpose. I’m growing in 5gal fabric pots. I have used lime to balance out to acidic soil. I have been using LST on her and have removed very little foliage.

Nute burn maybe