Hello crad,
I forget what
nutrients your using, but I wonder why you think you need micro-nutrients. If your using commercially made hydroponic nutrients they should have the micro-nutrients in them. That's the difference between hydroponic nutrients vs soil nutrients. Also I don't know of a complete micro-
nutrient supplement you can get. You will probably need to buy each element separately, and make your own to do so. I do see the picture with the yellowing leaf, and although a nutrient deficiency (or toxicity) is possible/probable, there could be environmental issues causing it too.
But one thing stands out to me from your post, that was about your water quality. That's probably the most overlooked factor for hydroponic growers (and a definite source for plant toxicities). Even if you just noticed visible sings of a problem now, the problem could easily have been caused/started weeks earlier. On the same token any change may not be able to be noticed for weeks into the future as well. I would start by making sure I was using good water quality (straight well, or rain water may have problems as too). Make sure I was mixing the nutrient solution appropriately, and check pH daily to make sure it's within range. Then pluck off the yellowing leaves, and wait a few weeks to see if there's improvement. Even if a few more leaves begin to yellow, it could be still be from damaged plant tissue from before (unless it's completely new foliage).