Review on 🐠 RuiLing 10pcs Air Pump Check Valves: A Reliable Solution for Aquarium Fish Tank CO2 Water Air Line Pump - One Way Non-Return Actuator Check Valve by Mandy Martin

So, after some trial and error, I found that the whistling is due to the check valve vibrating too much. That would have been fine at lower settings on my air pump, but as I increased the power the whistling was non-stop. All my tanks are in my room so that's not an option. They are all powered by air pumps and through trial and error I figured out how to make everything almost silent. For this check valve, the solution was as simple as placing the air pump on a small towel and placing a rock on top. the top of the check valve. Not the most elegant or aesthetically pleasing solution, but it works.