FYI Fittings are different. Luckily I had enough PVC to be able to cut and glue the new fittings and get my tank up and running. On the M1 I have been running it in a light vinegar and water solution and no whining. I ordered another coupler set from Ecotech so when it comes in I will try and see if the whine comes back when I add 5' of pressure to the cleaned pump.