Leafs getting brown spots, progesses to cover whole leaf

[DSK]

Indoor grow, using HID MH and HDS. Good ventilation and temp controlled to 75 deg avg.
7 gal pot.
Foxfarm Ocean Forest Potting soil. Foxfarm Big Bloom, Tiger Bloom and Grow Big nutes.
Also using CaliMagic Calcium/Magnesium supplements and have started using Superthrive vitamins.
PH in, with nutes close to 8. PH out is 6 plus.
Auto Flowering, feminized seed. Sativa dominant.
Problem first appeared around 40 days into grow.
Thought it might be a Calcium deficiency problem, but it won't go away.
Any suggestions?

[Eliot Pryor]

I had a similar situation and I'm blaming spider mites. I got rid of them with neem oil. Well I still use the neem oil at first sight so maybe saying I got rid of them is optimistic.

[DSK]

Thanks Eliot,
Thought I had looked pretty closely for any critters, and did not see any. Will look again, and probably carefully wipe effected leafs with neem oil just to cover all the bases.

[kingfish]

If you got Spider mites (The Borg) then stinky Neem oil ain't gonna do it. you need something more potent. Try this instead. You need a jewelers loop with at least 30x to see The Borg.