The Thomas 617 Wob-L Piston air system is compact and strong giving 1.16 cfm. @ 5psi and is only 1/7 hp. Handle ponds that are 30′ deep or run 2 air diffusers in 4-9′ of water. The right size to aerate and clean smaller ponds and reduce algae growth. Great for use in the winter to prevent fish kill and keep the pond open for swans, ducks or dock deicing.