Ira, My advice:
1: Remove carbon.
2: Do a 50% water change NOW with water you know is good.
3: raise KH back to 10 all in one hit with baking soda, (1 x Heaped teaspoon per 300 litres = 2DKH)
4: THEN LEAVE IT.
Feed sparingly.
There is nothing else you can do.
If after a week things havent changed do one more 50% water change.
CHECK YOUR WATER SOURCE FIRST.