All,
I've been lingering here as a newbie trying to piece together a DIY aeration design for my 1-3/4 acre pond that has a depth range from 4-12'. After reading the experiences of most folks here I concluded I will need 3-4 double diffusers and a whole bunch of sinking hose for a start. My plan is to install the pump near my home and bury 225' of 1" PVC pipe to a distribution header at the pond edge for balancing flow to the diffusers. Since my pump will be close to our rear porch area, I'm trying to find a pump that won't be intrusive from a noise standpoint. The purchase price and cost of running and maintaining the pump isn't an issue but I would like to install the quietest 1/2-3/4 HP pump possible. Unfortunately decibel ratings aren't available for the various makes and models so at this point I would like to reach out to any members here who have experience with both Rocking Piston and Rotary Vane designs. I do understand the Rotary Vane pumps push more air for a given HP but I need to keep noise as the primary deciding factor. Thanks for any feedback!

In my experience amount of noise decibels (db) is similar for both compressors rotary vane and rocking piston.
Type of noise from a rocking piston is different compared to a rotary. There has been past discussion here about the noise level of both compressors. See this previous discussion
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=39389

Many aeration compressors are manufactured by GAST Manufacturing. From their technical information the rotary vane operates at around 38 decibels (db) and their rocking piston operates at around 55 db (db's range 40-60+). Many 'places' that sell aeration products offer an insulated cabinet to help suppress compressor noise. For D-I-Y systems be sure to install a fan in the cabinet to keep the compressor cool.

Bill, This is perfect, and I just learned a valuable lesson on how to properly search for a topic. I went back only two years which yielded absolutely nothing. With the information you provided I should now be able to weigh my decision on noise and include efficiency since both pumps run much quieter than I anticipated. The Gast website had me worried when they listed <70 DB for their 1/4 and 3/4 HP pumps and I had nothing to compare to verses Rocking Piston. And definitely I will provide sound proof material in the cabinet. I appreciate the reply.

When you use a compressor in a cabinet or enclosure make sure there is very good ventilation. Commercial Cabinets for aerators always have a fan. TWO things are the enemy of air compressors MOISTURE and HEAT.

Understood Bill, Thanks!
After pondering all this information I'm re-routing my thought process all together. I've actually decided to purchase a 3/4 HP Gast rotary vane pump and give it a bench test to determine noise. If the noise isn't too loud I may mount the pump in my work shop which would place it in a clean and dry environment without the need for an enclosure. The run of 1" PVC would be about the same length and with the 3/4 HP compressor I should be able to turn over my pond ~2x a day running the pump from 10:00 PM to 7:00 AM. During this time my shop would be mostly unoccupied anyway.

Putting the compressor in the shop is a very good idea. I always encourage operating the compressor in some sort of building for several reasons. 1. pump runs cooler, 2. you can better check and monitor the daily operation of the pump system, 3. pump will be easier to change filters and/or take out of service for periodic vane rebuilds. 4. Pump will receive less influence and stress due to weather.

The 3/4 hp rotary is a very good choice for larger ponds. It produces close to twice the amount or volume of air as a 1/3 hp rocking piston.

People have also built DIY cabinets for their compressors to further reduce noise while maintaining cooling airflow.

There has been good previous threads about homemade cabinets for aeration systems. Cabinets can work well when they are built properly.