Deficiency or overdose? Wish I could post a pic

Hey there- wish I could upload via my mobile phone, but I can't right now. Perhaps it's futile to ask without a picture, but maybe I'll try anyways.

Leaves look healthy except for the fact they are loosing chorophyl. By that I mean, little pale blotches developing, but the color transition is faint. Barely noticeable under HPS. I'll try and post a picture tonight. I think it's due to an overdose of GH nova grow, 2.1EC. But I only see this on one plant. It may also look like an iron def.
Any suggestions?

...another possibility, could be soil pH? I have one of those soul pH probes, but it almost always shows 7.0...