I was all ready to queue up a GET A LINEAR AIR PUMP post then I read you only had one airstone to power and got disappointed.
For small applications before I got my Linear pump I used single whisper pumps and never had any complaints about them. I think I got rid of all mine when I downsized or else I'd send you one. I used the blue thunderdome looking ones Phil referenced above with 4 legs. That AP150 may be the ticket though. I used to have an ancient little single pump, clearly from the early 90s worked like a CHARM, was the quietest pump I had ever run (before Linear). Got to a point where I had to flip it upside down and put something heavy on top of it while running to keep it quiet but man it rivaled my Linear air pump in sound. They don't make them like that anymore. I go in fully knowing those little single pumps are only good for a handful of years.
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