Magnetic Drive Pumps
The magnetic drive pump has been a mainstay in the aquarium and fountain making industry for decades. With advances in manufacturing technologies the true magnetic drive pump was introduced into the pond industry several years back and has enjoyed brisk sales from consumers. Its small size and price make them a good choice for fountain statuary or very small pond systems. A true magnetic drive pump can be identified by the following characteristics:
- It contains an actual magnet at the core of its impeller assembly; 2. It has an impeller with straight or hinged paddles allowing it to spin in either direction; 3. The electrical motor is encapsulated in resin with the impeller assembly as only moving part; 4. Pump will consume very little power when operating; 5. Inexpensive purchase price.
In general you will find magnetic drive pumps from 40 GPH to about 3000 GPH flow. Advancing technologies have allowed for increases in flow but only to a certain point. The size and flow capacity of a magnetic drive pump are limited by the size of the actual magnet assembly. The magnet is made of a combination of rare earth materials. Up until the 1980’s this material was typically Alnico or Ferrite. At that time a new process was developed using Neodymium, which allowed a much stronger magnetic field and advances in manufacturing made the process affordable. The process of magnetizing this material leaves it ceramic- like and very brittle. In magnetic drive fountain and pond pumps you can identify a rare earth magnet by the resin or plastic sheathing placed over it for protection.
There are several pros and cons when using a magnetic drive pump:
The best benefit of magnetic drive pumps is the extremely low power consumption. Small pumps in the 40-200 GPH flow range often will consume only 2-10 watts. Larger magnetic drive pumps in the 1000-1300 GPH range average more towards 80-120 watts. Additionally these pumps are designed for continuous operation and will often last 5-7 years or more especially when run 24/7. Low purchase prices, extremely low operating costs, and the small sizes of these pumps make them a near perfect choice for statuary fountains and smaller water gardens.
Several drawbacks do exist for magnetic drive pumps and these prohibit them from meeting the needs of larger pond projects. With AC electricity (Alter-nating Current) the rotor changes directions each time power is applied to the magnetic drive pump. This changing rotation of the impeller means that it must be designed in a way that allows it to move water in either direction. This design restriction limits the practical size of pumps in the pond industry.
The main drawback to more powerful magnetic drive pumps is this issue with directionality of the impeller. He explains that in order to make a larger flow magnetic drive pump one needs to increase the size of both the actual magnet rotor as well as the inefficient impeller. A larger impeller assembly means a hotter operating temperature as well as more strain on the impeller shaft upon starting. A hot magnet draws calcium deposits to it and with enough buildup on the rotor the pump will seize up.
Additionally, impeller assemblies have a ceramic shaft on which they spin. The larger the magnet the more torque is placed upon the shaft upon each motor startup. Over time this torque creates stress upon the ceramic shaft until it finally snaps during a startup. A magnetic drive pump that is set in operation and remains running 24/7 will last many times longer than the same pump subjugated to frequent starts and stops.
Magnetic Drive Trends in the Pond Industry<