the older hailea models are loud. newer ones are much quieter. definitely agree with getting a compressor if your tank is larger(280 gallons and above), unless you only plan to keep the water temp at 28-29 degrees c Sent from Singapore Reef Club mobile app
My two cents can’t speak for the other Brand’s but I have a haelia HS28 and noise level is pretty much not noticeable. Have been running it for 3 years Sent from Singapore Reef Club mobile app