A lot of people end up getting the wrong pump when they’re putting together a fountain or pondless waterfall. If the pump is too powerful, they end up with jets of water shooting wildly out of the fountain or a sad little trickle. The mistake that most often leads to this miscalculation is choosing a pump based primarily on gallons per hour (GPH). This is the rate at which the pump moves water, and while it is indicative of the power of the pump and a very important number when choosing a pump for a pond, it isn’t quite the number you want to focus on when choosing for a fountain.
The number you’re looking for is the maximum lift (sometimes called “head” or “rise”). This is the measure of how high the pump is able to pump water, and it will usually be presented in inches. Keep in mind that this is the maximum height for the pump, which means that at that height you will usually get only a trickle. Instead, you want to choose a pump with a somewhat higher maximum lift than how high the fountain is. Remember to measure from where the pump will be sitting to the actual fountain outlet, then allow a bit more distance (for instance, for a 20 inch rise, you’ll probably want a 36 or so inch maximum lift pump).
There are a few other things that you will want to consider when choosing a pump, though lift is the most important.
- Gallons per Hour (Didn’t you just tell me to ignore this?). The rule of thumb, depending on just how much water you want coming out of the fountain, is 100 GPH per one inch diameter of fountain outlet.
- Pump dimensions. Check to make sure that the pump will fit wherever you’re going to be putting it.
- Discharge size. This is the size of the actual outlet on the pump. You want to check to make sure that the pump’s discharge size fits with the tubing that you’ll be using for the fountain’s plumbing. Having the right discharge size makes everything much simpler.