Could the high TDS be another issue with the substrate? When I first set up the tank the water was very cloudy for a couple days, even though I rinsed the gravel.
I'm guessing that though the water is clear there's still bits of the "dust" from the gravel floating around.
I will cut back on the water changes, I just like to keep things as clean as possible. I do not add minerals because I'm not entirely sure how much to add, and was thinking with the waters hardness the mineral content was okay.