CFM details listed on a pump are what it produces without resistance. It’s a good measuring tool when making pump comparisons and is relative to aerating a pond. CFM though, needs to be tied to HP and the ability of the pump to maintain a level of CFM against a level of pressure per square inch (PSI) and ultimately distribution through a diffuser. To put CFM into perspective, a linear pump can have approximately 6 – 8 CFM. A piston pump can have 3 – 5 CFM. A typical house fan can produce over 100 CFM. Comparing by CFM only, the house fan should be your best option, but in reality, it would come to a dead stop in a 1/4 inch of water. It doesn’t have the power or design to maintain that level of CFM against minimal PSI. The fan it is designed to move air with minimal resistance. This holds true when comparing linear pumps to piston pumps. Linear pumps generally have a higher CFM than piston pumps without resistance, but piston pumps have the power and design to hold a higher CFM against greater resistance.
Three Year Warranties on Pumps
With maximum operating PSI, most pumps of equal HP are relatively close in this manner too. However, the variation here can be greater than CFM because this is where the quality of components can come into play. Once a pump starts to experience resistance, you will ultimately find out if you have spent wisely regarding your pump. We feel so strongly about our pumps that we have an industry best Three Year Warranty!
What creates Resistance for a Pump
To be clear, everything connected to a pump creates pressure before ever getting to water. The inside diameter of airlines, a manifold, valves or number of valves, type of diffuser or number of diffusers, or anything else air must pass through before discharging into water. They all can create some form of resistance that results in PSI. This doesn’t mean a system with a manifold will cause a pump to experience more resistance than one without. On the contrary, these components are meant to assist a pump to properly deliver the most CFM at the system’s most crucial point – at the diffuser. However, when components are not sized or designed properly, the pump will work harder than it should before experiencing any pressure applied to the diffuser by water, where performance is judged.
One thing to keep in mind here is what’s keeping the pump cool. Do not under estimate the value of a properly design cabinet system. The hotter a pump operates, the shorter the life span.