Over the past two or three days, my HiBlow 120L has gotten noisy and as of this morning the difference is suddenly very noticeable.

I haven't been able to check it out. I have to leave for work here soon.

It's been pretty cold over the past few days with lows getting down to around 10 degrees. It's went through a much colder spell earlier in the winter and was fine. I don't know if the cold has anything to do with the noise though.

It's the first pump I've owned and I bought it and set it up last Spring. I have two lines approximately 100 ft. each running off of it. The disks are in about 4 feet of water and the line diameter is 1/2".

I don't know what is causing the noise but it's concerning. I don't know if ice buildup in the line is happening and if that would cause it. I don't know if it's the motor or the diaphragm. It still appears to be pumping out the same amount of air or at least making the same size boil of bubbles in the water. Any ideas on how I might trouble shoot this thing? TIA!