That's not possible, the main group of good fungi actually live in the plants . The other set is free in the medium, Endo and ecto . Your beni's won't interact with either of those fungi. They all work together in soil for the plant in nature.
Honestly, I have no idea what's going on here, and I kinda like it. I say have a pump recirculating all the time in the reservoir and another pump for the manifold on a timer for application. I don't understand why you would need filters? What are you planning on filtering? And no shutoff...
For sure man. That's a good number to be at anyways. As you drop your ppm lower watch the pH swing and you'll get a gist of how often you need to feed/flush.
Nute burn will show in new growth. Deficiency will normally creep up from lower in the plant. I don't think your over feeding it . Did u recently repot the plant? Damage to thee roots?
The leaves pointing up is normal when the lights come on. The roots can get discolored and it could be whats happening with the PPM you were running. Yeah hydroguard or some beneficial fungi is the next step. That will help so you don't have to stress over the water temp so much.
Was the pic taken shortly after you turned the lights on? That's could explain the upward reach. The roots don't look white, but it might just be the picture. Are they slightly discolored? Like a redish brown? Does the water smell like a fish tank at all?