Fungus or phosphorus? Pics

Hey all. Sooooo. I've had this grapefruit kush in veg for 6 weeks. She has constantly exhibited signs of what I think is a phosphorus/cal/mag deficiency since I first got her. However, I have also thought she may have a fungus. I am about to flower her and don't want to keep her in the same room with my other plants if I think this might be something that may spread towards the end of the cycle. That being said, she has been in close quarters with 5 other strains for her whole life and none of them are showing any signs of infection. But...when I got them, it seemed that they were all showing a bit of phosphorus def. That situation has cleared up in all of the other strains. Any advice would be greatly appreciated. I'll list all the specs below. Anybody familiar with this strain?
-grapefruit kush
-8 weeks from clone
-in fox farms ocean forest / 5 gal
-water ph 6.6 always (with or without nutes)
-ppm done according to ff online chart for plant life/cycle
-nutes are ff grow, cal mag.
-Tried upping cal, mag and phosphorus. She seemed to respond a bit but not too much. Don't want to od her. Additional p was given with a weak dose of tiger bloom
-affected leaves come right off when touched. No resistance whatsoever.
- seems to affect older leaves but does also appear on smaller/newer leaves
Hope someone can advise. Let me know if you need more info/photos. Thanks.
O

Anybody?

So im a first time grower but just calm down and sit back and think ....hey! It is a weed! Thats nit just the name it grow very easy its the thc and cbd that ur Trying to get higher levels of so id think ur either over watering or ur using the wrong or to much nutes plz correct me if u hear different like I said first time for me

Thx, but I'm sure It's none of those things. The plant is a three foot tall bush that will finish around 5ft. It's not about just letting it grow. It's about optimization.

Need pics of whole plant

Hey buddy.

I don't see any signs of fungus, but do I see white stuff on the leaf of the first pic? Could you take a pic of the whole plant? Knowing where the damage is occurring can help narrow things down. The rusting makes me think K or mag, but it could be a lockout causing this. How often/how much do you feed?

Thanks for the replies, guys. Here are couple shots of her sativa glory. Ps. That white powder is some cloning hormone that I slipped with, not mildew/mold.

I'm with the P/K deficiency school of thought.

I feed every other watering. Ph, ed, ppm all to specs on charts.

Thanks, snaps provolone. I just gave her a dose of p/k. Any thoughts on a good p/k supplement that could be added to regular feelings? She seems like she just might be a phosphorus hog.