I'm looking back and I see 2 more potential issues:
1) you say you adjust the water before adding it to the res. Do you adjust the res solution after? You may need to. pH adjustment shoudl be the LAST thing you do before walking away from a freshly filled res.
2) Your city water is relatively soft. You should run calmag up to 250ppm before adding any nutes to the res, then add your nutes after, then adjust pH.
stinkyattic Reviewed by stinkyattic on . light green spots. Pics! Ok, two of my plants have been starting to show some light green spotting and the leaves with the spots have curled into a taco like shape. PH is right around 6.8 and nutes are at 770. I'm going to mix up a new batch of nutes today because I had a water spill with the draining and I'm now low on water in my res. That and I need to add two more buckets to my system. Rating: 5