Mag def and what else?

[Bnelly]

I have what I believe to be a Mg def, from the brown rusty spots on the lower leaves. However the new growth is also looking kind of weird, almost like there isn't enough chlorophyll being produced in the areas.
Reasons for Mg def, I have pretty hard tap water and I was adding cal mag to it, so i believe the excess Ca has locked the Mg out. I have since been looking at grabbing some epsom salt to get the Mg without too much Ca

Strains: Blueberry Kush (bigger) and Granddaddy Purple
Media: 3:1 FFOF/HF with 20% perlite in 5 gal fabric pots
Nutes:
Age Old Bloom (only about 1/4 - 1/2 strength in the GDP. BBK was flushed out about 4 days ago to fix a nute burn, which it seems to have done)
Cal/Mag + was using 5 ml/gal or full strength
Liquid kelp 1 tbsp/gal every other feeding

Ph: always adjust to ~6.5 before feeding
Light: growing out doors
Temps: Day - mid-high 60s. Night - mid-high 50s
RH: ~50-60ish

I also found a single red spider mite 2 days ago and sprayed all plants with neem oil, will be spraying again with agromagen in the next 2 days

 

[Bnelly]

So i was very brash and single minded when I made this thread, I was so focused on one symptom that I missed a couple more indicators, mainly lower leaves contorting and curling. I went and did another test of my tap water, and it appears to be between 100-250 ppm, I only have test strips.
Now im thinking its a Ca def due to the description from this book. Plants do not look sickly and still feel pretty healthy.