IMHO, there is no such thing as an "over instrumented water cooling system". I could buy an AIO cooler for my CPU and use the factory cooler on my GPU, but what fun is that?
I am curious about this Bosch HFM6 sensor,, which according to a quick Google search is called a Hot-film Air-mass Meter. It appears to be used in automobile engines to help ensure an optimum ratio between fuel and air (stoichiometric ratio). I found a Volkswagen PDF document that shows the hot-film air-mass meter installed between the engine air intake and the air filter. This document did not list the dimensions of this device, but based on the diagram it looked pretty big, and not like something that could be used in a computer cooling system. I am intrigued, so did a little digging, and found that the
OMRON D6F series and
Honeywell Zephyr HAF Series are much smaller mass air flow (MAF) sensors. OMRON says their MAF sensors can detect a single butterfly wing flap. Maybe something like this would be more appropriate inside a computer case? My other concern is that these devices have to be in the air intake path. In a computer liquid cooling loop, the cooling fluid path is constrained by the reservoir, pump, tubing, blocks, and fittings, but fans push and/or pull case and ambient air with no real path constraint. How would you get all of the air passing through a radiator to then pass only through a mass air flow sensor like this?
DATA - Whether an Aquaero can accept and interpret the data coming from an air mass flow sensor is a separate issue. I think the Bosch HFM6 outputs a 5VDC square wave at a frequency proportional to the measured air mass flow. The OMRON D6F series includes models that output pulses, analog voltage, I2C, RS485, and CAN Bus. Since the Bosch outputs 5VDC pulses, I think an Aquaero could count the number of pulses per unit time, but it would have to do some scaling. If you went with one of the OMRON or Honeywell MAF sensors, you could connect its output to a small Micro-Controller (MCU) like a Raspberry PI RP2040 Pico or an Espressif ESP32 and write a little Python program that would read the incoming data (I2C, CAN Bus, etc.) and output TTL pulses on a GPIO pin that the Aquaero could measure. If you used an MCU with a decent ADC, it could read an analog voltage which the Python code would convert to a TTL pulse train that the Aquaero can read. OMRON and Honeywell provide the transfer functions or lookup tables required for a downstream device to interpret the data in whatever format the sensor outputs - analog voltage, RS485, I2C, or CAN Bus.