Ideas? rubble or bio balls?

[seashells]

We are just setting this tank up in our store. I would like to put small bits of live rock & rubble in the second chamber instead of the bio-balls. Does anyone know how full it should be? I thought about 4-6" loose rubble would be good. Does this quiet the noise? Any other thoughts?

[kwirky]

what kind of noise are you trying to quiet?

[seashells]

the sound of the water flow. It is better now that we put the top tray in the right way. oops