Aspen Aeration 1/4th Hp Complete Aeration KitsThis Complete Kit for 1 acre ponds Includes a 1 4 Hp Oil less Rocking Piston Air Pump, a 2 way manifold with a pressure gauge, two 100 ft rolls of 3 8" weighted tubing, and two 9 inch diffusers with bases The manifold includes an oil filled pressure gauge to reduce indicator vibration. Also attached is a pressure relief valve which opens at approximately 25 psi to prevent damage to the compressor The self weighted air hose is very heavy duty and