We bought the unit used. It had been stored with pink ant-freeze in it. It sat for over a year before it was used again. We brought it online last month. We had readings of 350 + or -. Our Katadyn put out readings of 90 PPM all the time. So we ran 2 flushes, the alkaline wash and the acid wash. Now we get 150- 350 ppm. My biggest gripe is it only makes 3- 4 gallons an hour. It' supposed to make 6. But my Katadyn was supposewd to make 1.5 and it only made 1 so I was wondering waht the problem was.