I was going to say this! In my 200 gallon with sump is dead quiet literally my 10 gallon fry tank is louder.my sump on my 240 is quieter than my sunsun and fx5. it makes noise when it is time to change the filter sock.
My filter floss gets clogged and makes some water noise but its faint and thats when I need to change it. My 10 gallon fry tank is over filtered with sponge filters hence why its loud with the damn bubbles.