Review on Enhanced Tetra Whisper Air Pump: Optimal Airflow with Minimal Noise by Libby Walker

I have been using these pumps for ten years. They are cheap and last about two years. Membranes dry out and delaminate like all rubber products break down. They mature on the shelf, so try to get them from a major retailer. The problem is that rubber replacement parts cost the same as the block. I extended its life by lubricating the diaphragms with plumber's grease once a year. They are very quiet, the sound of the water is louder than the pump. The output isn't as advertised, so I'd go one size larger. Replace air stones regularly. A noisy pump is a sign of back pressure. Leaving your old pumps for spares, went to lubricate the diaphragms and ripped one of the outlets. If I kept some of the old ones I would have a spare case. Quiet, cheap and reliable pump that lasts two years, it seems that all other brands are worse. At least Tetra and Marineland have someone on the phone.