Noisy Flex 57 Pump

Sorry to read about this. I don't / have never had a Fluval Flex but have had occasional or intermittent unwelcome sounds from previous filters or their vibrations in the past. Usually, I've managed to resolve these by moving the cable which itself was vibrating against the lid/tankwall, removing the impeller to ensure that there isn't a grain of sand stuck to it (with a cotton bud) or ensure that it's sitting properly in it and not ever-so-slightly tilted, or changing the filter's location in the tank altogether. Another option which works for some people is to tilt it back and forth at a range of angles including upside down underwater to ensure that any trapped air bubbles are released.

If, having tried all these to no avail, it might be worth contacting Fluval for their advice.  It might be that a replacement is required.  Only after doing all of these, and if the problem still hasn't resolved, would I then consider another filter if I simply can't live with the sound or the fish seem stressed by it.  If you did opt for another filter ultimately, then generally Eheim filters seem to get excellent reviews for how quiet they are.

Hope that helps.

Thanks for reply.
I tried everything but the humming of the pump is just resonating through the tank. Its like having a fridge freezer in the room so annoying. Think I'm just going to buy a eheim compacton 600. Heard they are very quiet and adjustable.