Hi Steve,
I hope this contest will help answer many questions about keeping discus.
My gh and kh is less than 1 also. I don't understand your water company tds of 5ppm. Some people's ro water is sometimes higher than 5 depending on the water source. At some point you may want to get your own tds meter so you can track it yourself when you are breeding discus. My tap water tds is quite low, 29.5 ppm, 64.2 ms. Great for breeding but will have to see how it grows out discus. So far it seems to be fine.
Bill
My tap ppm
My tap ms