help me design a silent system!

[trilinearmipmap]

I had the same concerns. Nothing makes noise from my tank except the EuroReef.

I used the Herbie's silent sump system. If I could have found a large enough Eheim return pump I would have got one, instead I used a Mag 12. I put 2 layers of closed-cell foam under the sump. I was going to insulate the inside of the stand with sound-deadening foam but it is not necessary.