The patches are an early sign of a calcium deficiency... and this is usually caused by either a nitrogen toxicity (which I don't see) or a pH that's way out of range. If you've not been measuring your pH, now is the time to do it... your tap water may be 6.8 but the additions of nutes can drastically alter that reading... and if you're growing in coco, even 6.8 is much too high - you want to get it to 5.8-6.0 when they're vegging and 6.0-6.3 in flower. If the problem is pH, throwing any amount of calmag at her won't do a bit of good.
Good luck!
Oh yeah - fungus gnats... don't ignore them... get yourself some Mosquito Bits and follow the directions... you need to soak the granules in some water for 30 minutes and then, after straining the granules out, use the water to water your plant... works a treat.