ESP8266 and Fermion MEMS Microphone as water flow sensor

hello,

am using the MEMS microphone attached to a water pipe as a water flow sensor.

when the valve is closed I get 1.6V ….

However when the valve is on and hot water flows through the pipe I don't see a difference to the voltage. 

My sketch as follows

  - platform: adc

    pin: A0

    name: "Water flow Sensor"

    id: "water_flow_sensor"

    icon: mdi:water

    update_interval: 0.5s

    filters:

      - multiply: 3.3

      - sliding_window_moving_average:

          window_size: 10

          send_every: 1

      - or:

          - throttle: 180s

          - delta: 0.02

any help would be much apreciated!!!

thank you in advance !!

Gerasimos