here is one to consider:

This system is ideal for 1 to 3 acre irregularly shaped ponds. It includes a 115-volt 1/3 HP Rocking Piston Compressor, 3-valve outlet with pressure relief valve, 400 feet of 3/8� weighted airline, 3 W4 WaterBug diffusers and fittings. The system comes with complete installation, operation and maintenance instructions.

This system includes the following:
1/3 HP Rocking Piston Compressor
400 feet of 3/8" Heavy Duty Weighted Airline
3 ea. WBB4 Diffusers
3-valve Outlet with Pressure Relief
All Necessary Fittings
Complete Installation, Operation and Maintenance Instructions
NOTE: 3 hole brick is required (not included) for installing diffuser.

Size Pond This System Will Aerate Max Depth Max Pond Size
3-4 feet 1/2 acre
5-8 feet 1 acre
9-12 feet 2 acres
13-16 feet 3 acres