Air pumps

Air pumps. The smallest, quietest air pump is the one I'm after, since I don't need air pressure sufficient to run a wall o' bubbles or a bubble volcano: just a discrete sponge filter  here and there in 10-gallon tanks. The smallest Rena and Whisper 10 each have their fans. We're living through a design phase where most consumer products, even cars, imitate either a computer mouse or a sneaker: Rena is vividly a mouse. The Fusion 200 divides the air flow into two opposing chambers in an attempt to damp sympathetic vibration. As for bedroom quiet, all air pumps seem to develop vibration hum with time, in part as their diaphragms age and stiffen. Reducing back pressure extends the life of a diaphragm; if there is no dial to adjust airflow, you can install a bleeder valve in the air line.
 
Damping that hum. Air dampens vibration noise, but an air pump that shares a counter surface with a tank, or even one on the inside shelf of the cabinet stand, can transmit quite a roar. Though the air pump may sit on its own rubber feet and hum quietly, if I put my ear to the tank, transmitted vibration makes it sound like the engine room of the Titanic in there. Setting the pump on a stiff cork hot plate supported on several thick rubber bands lying on their sides helps muffle the hum. A stiff, unused kitchen sponge, scrubber face upwards, also makes a firm, sound-deadening base. But the best arrangement is to put the pump, with its sound-insulating base, on a bracket screwed to the wall. Make sure the bracket has a lip round it, because those pumps are made for walkin' and that's what they're gonna do.