I have a Solido Smart, it has the air pump inside a sealed housing inside the neck of the tank (under a double-skinned lid) A hose is fed in from a remotely-mounted inlet, which in our case is beside a hedge and unnoticeable. It's an SBR system so the pump doesn't run all the time anyway, but the only time any sound is noticeable is during the pumpout phase and it's more of a splashing/bubbling sound. Highly recommended.