Indoor Big deficiency but which one?

[MrMrMr]

I'm sure im having a deficiency but I'm not sure which one it is. First off I'm in dwc, ppm is 300. It goes down about 30 points a day and the ph is going up. I noticed the leaves were turning yellow between the veins, but they gradually went from yellow to purple. The stems and the veins are purple as well. Is this cal mag or phosphorus deficiency? I turned the temp down for a week to 70° last week to dry some other stuff so I'm not sure that's a factor.

Hlg 550 rspec
Temp 79
Rh 50
1 is West coast og the other is gorilla glue auto
I'm using gh 3 part with liquid koolbloom so I would think I'm getting enough phosphorus and potassium should i make my solution 50% cal mag or what?
I'm stumped

 

[Simplicio]

These things are hard to figure out.
I'm a light feeder, but 300 ppm is less than I'd use.
There could be some light burn, depending on light distance.

I'd add enough CalMag to slowly get ppm up to around 400, and maybe raise lights.

 

[Arthur]

Not a DWC guy, but Phosphorus and calcium will interact. High calcium loads locking out Phosphorus kinda thing.