Originally Posted by diwu13
Hm... are you sure your kH and gH test is correct out of the tap? Or is your TDS measurement in degrees? Generally, if you're using a TDS meter it will measure in ppm, whereas the kH and gH tests are in degrees. In which case your TDS should at least be ~38.
The numbers you quoted are from the water out of the RO/DI filter. My tap water is:
KH 5 (drops to color change, API test kit)
GH 6 (drops to color change, API test kit)