This is a little late but I'm calling BS on the back pressure. I run a S8 and a S6, both choked back by manifolds. They are DEAD silent.Well, guys, the Varios 6 humming is louder than our refrigerator that is 5 feet wide. I have traded emails with Carlos of CoralVue, he is responsive, but didn’t move the needle at all. Has not called me and immediately jumped to blaming manifold and reduction to 3/4” hard piping as contributors to back pressure. Not happy with their quick to blame approach (keep in mind, I told them that I have run the pump at all speeds from 10% to 100% in 10% increments, same noise level). They still think its the manifold/back pressure.
However, different story with the guys at @Bulk Reef Supply. Talked to them and ordered another Varios 6. Will be an easy swap, hope its the pump defect, at least I will be able to tell. However, if I continue to have the same problem, BRS offered to work with me on returning both pumps, buying Varios 4 and doing a store credit etc. Bought most of my stuff from BRS so far and they have just shown why I should continue to do so. First reach out to them with a dilemma and they were super helpful. Hoping to swap the pump on Sat and fingers crossed that the new one is quiet. I can then send the defective one to Carlos with a nice “its not the manifold” note.
On a separate subject, great feedback from Ecotech customer service on noisy MP40. They said if it doesn't break in in 2 weeks, they will send a replacement wet side.