I recently installed a whole house carbon filter, which consists of a 13x54 tank, 2.5 cu ft of GAC and a Fleck 7000SXT head. Everything appears to be functioning correctly except I'm surprised by the noise produced when running through the backwash and rapid rinse cycles. Because of the volume of carbon, it is setup to backwash at 10GPM (and does fill a 5 gal bucket in about 29 seconds). The drain line is 3/4" PVC. The backwash and rapid rinse cycles are both setup at 10 minutes each, on a 7 day cycle.
From what I can tell, the noise seems to be cavitation around the DLFC washer, which may be standard at this high of a flow rate, but louder than I was expecting. I found advice on clearwatersystems.com that recommended running a backwash, moving to bypass, pulling out the button, moving the system back in service for a few minutes to flush the drain of air, and then putting the button back in. I tried this, but as soon as the system is put back in bypass, the drain line empties and is filled with air again.
My house water pressure is 52psi, and the main line is 1"CPVC leading into and out of the whole house carbon filter. After the filter I have a water softener with a Clack WS1 head that is substantially quieter (but of course at a lower flow rate).
Has anyone else experienced such a loud backflush / any ideas to quiet it?