Pond Boss Forums AERATION Systems questions CFM VS PSI

Notes - comments: a check valve does not prevent back pressure. A check valve stops or prevents water from leaking into the airline past the valve. Water in the airline does cause excess, unnecessary, back pressure on the pump when the pump restarts - this shortens compressor life span. Be aware that 3/8" ID hose is fairly small diameter for common large pond aeration. Smaller diameter hose can cause reduced air flow and some increased back pressure due to the narrow diameter hose tending to resist flow of air inside the hose. The amount of back pressure in these cases is highly determined by the length of hose, longer hose = increased back pressure as hose or pipe diameter is reduced/smaller. There are charts of air flow for this. If you are using only 50 ft of 3/8"ID hose, IMO little back pressure will be measured with good air gauge. At 100+ft consider 1/2" ID hose especially when the pump is near its rated peak for normal running pressure.

Most single diffusers require around at least 0.5cfm for normal efficient operation. The less cfm a diffuser receives the fewer bubbles it makes and the less water it moves. Excess cfm to a diffuser causes the slits to over expand, makes bubbles larger and less air lift efficiency occurs.